diff --git a/crates/xfa/src/data.rs b/crates/xfa/src/data.rs
index cb3b80a0c7..09c8252fa8 100644
--- a/crates/xfa/src/data.rs
+++ b/crates/xfa/src/data.rs
@@ -55,6 +55,10 @@ pub struct DataNode {
     pub name: String,
     pub text: String,
     pub children: Vec<DataNode>,
+    /// Whether the element is a data group even with no children: marked
+    /// `xfa:dataNode="dataGroup"` (XFA 3.3 p. 150), or a multi-select list's group emptied of its
+    /// picks here, which the packet writer marks so.
+    pub group: bool,
 }
 
 /// A path into the data: `(name, index among same-named siblings)` per level.
@@ -150,10 +154,21 @@ impl DataNode {
     pub fn apply(&mut self, op: &DataOp) {
         match op {
             DataOp::Value { path, text } => {
-                if let Some(n) = self.ensure(path)
-                    && n.children.is_empty()
-                {
-                    n.text = text.clone();
+                if let Some(n) = self.ensure(path) {
+                    // A multi-select list's picks, one `value` each (see `value_at`), told apart
+                    // as the packet writer does: `value` leaves only, or a group holding none.
+                    let picks = if n.children.is_empty() { n.group } else { n.children.iter().all(|c| c.name == "value" && c.children.is_empty()) };
+                    if picks {
+                        n.children = text
+                            .split('\n')
+                            .filter(|v| !v.is_empty())
+                            .map(|v| DataNode { name: "value".into(), text: v.to_string(), ..Default::default() })
+                            .collect();
+                        // Emptied, it is still a group, and takes picks again.
+                        n.group = true;
+                    } else if n.children.is_empty() {
+                        n.text = text.clone();
+                    }
                 }
             }
             DataOp::Instances { parent, name, count } => {
diff --git a/crates/xfa/src/data/merge.rs b/crates/xfa/src/data/merge.rs
index 0aefc634b5..0d573c71a9 100644
--- a/crates/xfa/src/data/merge.rs
+++ b/crates/xfa/src/data/merge.rs
@@ -271,6 +271,44 @@ fn merge(text: &str, within: Within, op: Op, warnings: &mut Vec<String>) -> Merg
     Merged::Changed(out)
 }
 
+/// Whether `node` is a multi-select choice list's data group: element children only, every one
+/// a `value` holding text alone; or, with no children, an element marked `xfa:dataNode=
+/// "dataGroup"`, as a group with no picks is written (XFA 3.3 p. 150).
+fn is_value_group(node: roxmltree::Node) -> bool {
+    let blank = node.children().filter(|c| c.is_text()).all(|c| c.text().is_some_and(|t| t.trim().is_empty()));
+    let mut elements = node.children().filter(|c| c.is_element()).peekable();
+    if elements.peek().is_none() {
+        return blank && marked_data_group(node);
+    }
+    blank && elements.all(|c| c.tag_name().name() == "value" && !c.children().any(|g| g.is_element()))
+}
+
+/// Whether `node` carries `xfa:dataNode="dataGroup"`.
+fn marked_data_group(node: roxmltree::Node) -> bool {
+    node.attribute((XFA_DATA_NS, "dataNode")) == Some("dataGroup")
+}
+
+/// The edit that marks the data group `node` as one, so that emptied of its picks it still loads
+/// as a group and not as a data value (XFA 3.3 p. 150): `xfa:dataNode="dataGroup"` added to its
+/// start tag, with the namespace declared there when the packet has no prefix for it.
+fn mark_data_group_edit(src: &str, node: roxmltree::Node) -> Option<Edit> {
+    let range = node.range();
+    let tag_end = start_tag_end(src, &range)?;
+    // Before `/>` of an empty tag, else before `>`.
+    let at = if src.get(..tag_end)?.ends_with('/') { tag_end.checked_sub(1)? } else { tag_end };
+    let text = match node.lookup_prefix(XFA_DATA_NS) {
+        Some(prefix) if !prefix.is_empty() => format!(" {prefix}:dataNode=\"dataGroup\""),
+        _ => {
+            // A prefix no namespace in scope is bound to, so declaring it rebinds nothing.
+            let prefix = (0..16)
+                .map(|i| if i == 0 { "pcxfa".to_string() } else { format!("pcxfa{i}") })
+                .find(|p| node.lookup_namespace_uri(Some(p)).is_none())?;
+            format!(" xmlns:{prefix}=\"{XFA_DATA_NS}\" {prefix}:dataNode=\"dataGroup\"")
+        }
+    };
+    Some(Edit { start: at, end: at, text })
+}
+
 /// The edits that put `wants` into the `data` element.
 fn merge_values(src: &str, data: roxmltree::Node, wants: &[Want], edits: &mut Vec<Edit>, warnings: &mut Vec<String>) {
     // Element children by local name, per element visited (built once each).
@@ -311,6 +349,44 @@ fn merge_values(src: &str, data: roxmltree::Node, wants: &[Want], edits: &mut Ve
                 continue;
             }
             let current: String = node.children().filter(|c| c.is_text()).filter_map(|c| c.text()).collect();
+            // A multi-select choice list is bound to a data group of `value` elements, one per
+            // pick, and its value is theirs joined by newlines (XFA 3.3 p. 198); a new pick
+            // replaces them all, as in Acrobat (p. 199).
+            if is_value_group(node) {
+                // Every text segment of each `value`, as `current` reads a leaf (a comment may
+                // split or lead it).
+                let held: Vec<String> = node
+                    .children()
+                    .filter(|c| c.is_element())
+                    .map(|c| c.children().filter(|t| t.is_text()).filter_map(|t| t.text()).collect())
+                    .collect();
+                // Pick by pick: one `value` holding a line break is not two picks.
+                let wanted: Vec<&str> = w.text.split('\n').filter(|v| !v.is_empty()).collect();
+                if held.iter().map(String::as_str).eq(wanted.iter().copied()) {
+                    continue;
+                }
+                let inner: String = wanted.iter().map(|v| format!("<value>{}</value>", escape(v).0)).collect();
+                // Emptied, the group keeps saying it is one (XFA 3.3 p. 150).
+                let needs_mark = wanted.is_empty() && !marked_data_group(node);
+                let mark = if needs_mark { mark_data_group_edit(src, node) } else { None };
+                if needs_mark && mark.is_none() {
+                    // No marker can be written (no free prefix): emptied, the group would load
+                    // as a data value, so it keeps its picks and the skip is reported.
+                    skipped(warnings, STRUCTURED, &w.som);
+                    continue;
+                }
+                match replace_edit(src, node, &inner) {
+                    Some(e) => {
+                        edits.extend(mark);
+                        edits.push(e);
+                    }
+                    None => skipped(warnings, STRUCTURED, &w.som),
+                }
+                if dropped {
+                    skipped(warnings, CONTROL, &w.som);
+                }
+                continue;
+            }
             if node.children().any(|c| c.is_element()) {
                 let all: String = node.descendants().filter(|c| c.is_text()).filter_map(|c| c.text()).collect();
                 // Ignore existing XML indentation, but not whitespace in the accepted value.
diff --git a/crates/xfa/src/data/path.rs b/crates/xfa/src/data/path.rs
index 71f089112e..fd20b39d81 100644
--- a/crates/xfa/src/data/path.rs
+++ b/crates/xfa/src/data/path.rs
@@ -1,12 +1,14 @@
-use super::{DataNode, DataPath, Field, MAX_DEPTH, MAX_NODES, Node, SomIndices, Template};
+use super::{DataNode, DataPath, Field, MAX_DEPTH, MAX_NODES, Node, SomIndices, Template, XFA_DATA_NS};
 
 fn to_node(n: roxmltree::Node, depth: usize) -> DataNode {
     let name = n.tag_name().name().to_string();
     let children: Vec<DataNode> =
         if depth < MAX_DEPTH { n.children().filter(|c| c.is_element()).map(|c| to_node(c, depth + 1)).collect() } else { Vec::new() };
-    // The text of a leaf is its value; a container's own text is whitespace.
-    let text = if children.is_empty() { n.children().filter_map(|c| c.text()).collect::<String>() } else { String::new() };
-    DataNode { name, text, children }
+    // The text of a leaf is its value (its text nodes: a comment is not part of it); a
+    // container's own text is whitespace.
+    let text = if children.is_empty() { n.children().filter(|c| c.is_text()).filter_map(|c| c.text()).collect::<String>() } else { String::new() };
+    let group = n.attribute((XFA_DATA_NS, "dataNode")) == Some("dataGroup");
+    DataNode { name, text, children, group }
 }
 
 /// The `xfa:data` element of the datasets packet in `xdp` (or a bare datasets document), as a
diff --git a/crates/xfa/src/tests.rs b/crates/xfa/src/tests.rs
index d688c8312c..43d6633c56 100644
--- a/crates/xfa/src/tests.rs
+++ b/crates/xfa/src/tests.rs
@@ -4815,3 +4815,126 @@ fn a_template_inside_the_data_is_not_the_form() {
     let real = "<xdp:xdp xmlns:xdp=\"http://ns.adobe.com/xdp/\"><template xmlns=\"http://www.xfa.org/schema/xfa-template/3.3/\"><subform name=\"form1\"/></template></xdp:xdp>";
     assert_eq!(parse(real).unwrap().0.root.common.name.as_deref(), Some("form1"));
 }
+
+/// A multi-select choice list is bound to a data group of `value` elements, one per pick, and its
+/// value is theirs joined by newlines (XFA 3.3 p. 198). New picks replace the group's `value`
+/// elements, values off the list included, as Acrobat discards them (p. 199): the group was left
+/// as it was, so the old picks came back on reading, in the datasets and in the scripts' data.
+#[test]
+fn a_multi_select_lists_data_group_takes_its_new_picks() {
+    let shell =
+        crate::fixtures::static_shell("<form1><page1><grains><value>rye</value><value>barley</value><value>wheat</value></grains></page1></form1>");
+    let mut doc = Document::open(Arc::new(shell)).unwrap();
+    let path = som_to_path("form1[0].page1[0].grains[0]");
+    assert!(write_data_value(&mut doc, &path, "wheat\nmillet & oats").unwrap().written);
+    let data = crate::script::data_of(&doc).unwrap();
+    assert_eq!(data.value_at(&path).as_deref(), Some("wheat\nmillet & oats"));
+    assert_eq!(data.count(&path, "value"), 2, "one value element per pick");
+    assert!(!write_data_value(&mut doc, &path, "wheat\nmillet & oats").unwrap().written, "the same picks change nothing");
+    assert!(write_data_value(&mut doc, &path, "").unwrap().written);
+    assert_eq!(crate::script::data_of(&doc).unwrap().value_at(&path).as_deref(), Some(""), "nothing picked");
+    // Emptied, the group is marked as one (XFA 3.3 p. 150), so it is still written as picks.
+    let xdp = crate::read_packets(&doc).unwrap().unwrap().xdp;
+    assert!(xdp.contains("<grains xfa:dataNode=\"dataGroup\"></grains>"), "{xdp}");
+    assert!(
+        write_data_value(
+            &mut doc,
+            &path,
+            "rye
+millet"
+        )
+        .unwrap()
+        .written
+    );
+    assert_eq!(crate::script::data_of(&doc).unwrap().count(&path, "value"), 2, "picks again, not text");
+    // A pick split or led by a comment is read whole: the same pick is no change, and clearing
+    // a pick that reads as empty through its first segment alone still clears it.
+    let commented =
+        crate::fixtures::static_shell("<form1><page1><grains><value><!-- a -->rye</value><value>whe<!-- b -->at</value></grains></page1></form1>");
+    let mut doc = Document::open(Arc::new(commented)).unwrap();
+    assert!(
+        !write_data_value(
+            &mut doc,
+            &path,
+            "rye
+wheat"
+        )
+        .unwrap()
+        .written,
+        "the same picks, read past the comments"
+    );
+    assert_eq!(
+        crate::script::data_of(&doc).unwrap().value_at(&path).as_deref(),
+        Some(
+            "rye
+wheat"
+        ),
+        "and read back without them"
+    );
+    assert!(write_data_value(&mut doc, &path, "").unwrap().written, "cleared");
+    assert_eq!(crate::script::data_of(&doc).unwrap().count(&path, "value"), 0);
+    // Where `xfa` names another namespace and `pcxfa` is taken too, the marker's prefix is a free
+    // one, declared on the group, so no attribute in scope changes meaning.
+    let shadowed = crate::fixtures::static_shell(
+        "<form1><page1><grains xmlns:xfa=\"urn:other\" xmlns:pcxfa=\"urn:taken\" pcxfa:note=\"x\"><value>rye</value></grains></page1></form1>",
+    );
+    let mut doc = Document::open(Arc::new(shadowed)).unwrap();
+    assert!(write_data_value(&mut doc, &path, "").unwrap().written);
+    let xdp = crate::read_packets(&doc).unwrap().unwrap().xdp;
+    assert!(xdp.contains("xmlns:pcxfa1=\"http://www.xfa.org/schema/xfa-data/1.0/\" pcxfa1:dataNode=\"dataGroup\""), "{xdp}");
+    assert!(xdp.contains("xmlns:pcxfa=\"urn:taken\" pcxfa:note=\"x\""), "the taken prefix keeps its namespace: {xdp}");
+    // With every candidate prefix taken, no marker can be written: the group keeps its pick
+    // and the skip is reported, rather than emptied into what would load as a data value.
+    let taken: String = (0..16).map(|i| if i == 0 { " xmlns:pcxfa=\"urn:t\"".to_string() } else { format!(" xmlns:pcxfa{i}=\"urn:t\"") }).collect();
+    let crowded =
+        crate::fixtures::static_shell(&format!("<form1><page1><grains xmlns:xfa=\"urn:other\"{taken}><value>rye</value></grains></page1></form1>"));
+    let mut doc = Document::open(Arc::new(crowded)).unwrap();
+    let r = write_data_value(&mut doc, &path, "").unwrap();
+    assert!(!r.written && r.warnings.iter().any(|w| w.contains("structured content")), "{:?}", r.warnings);
+    assert_eq!(crate::script::data_of(&doc).unwrap().value_at(&path).as_deref(), Some("rye"));
+    // One `value` whose text holds a line break is one pick, not the two it would join to.
+    let one = crate::fixtures::static_shell(
+        "<form1><page1><grains><value>one
+two</value></grains></page1></form1>",
+    );
+    let mut doc = Document::open(Arc::new(one)).unwrap();
+    assert!(
+        write_data_value(
+            &mut doc, &path, "one
+two"
+        )
+        .unwrap()
+        .written,
+        "two picks replace the one"
+    );
+    assert_eq!(crate::script::data_of(&doc).unwrap().count(&path, "value"), 2);
+    // The in-memory data, which scripts read before the packet is written, follows the same rule.
+    let mut tree = crate::script::data_of(
+        &Document::open(Arc::new(crate::fixtures::static_shell("<form1><page1><grains><value>rye</value></grains></page1></form1>"))).unwrap(),
+    )
+    .unwrap();
+    tree.apply(&DataOp::Value { path: path.clone(), text: "millet\nwheat".into() });
+    assert_eq!(tree.value_at(&path).as_deref(), Some("millet\nwheat"));
+    // Emptied in memory, the group still takes picks, not text.
+    tree.apply(&DataOp::Value { path: path.clone(), text: String::new() });
+    assert_eq!((tree.count(&path, "value"), tree.value_at(&path).as_deref()), (0, Some("")));
+    tree.apply(&DataOp::Value { path: path.clone(), text: "rye\nmillet".into() });
+    assert_eq!((tree.count(&path, "value"), tree.text_at(&path)), (2, Some("")), "picks again, not text");
+    assert_eq!(tree.value_at(&path).as_deref(), Some("rye\nmillet"));
+    let tree_of = |data: &str| crate::script::data_of(&Document::open(Arc::new(crate::fixtures::static_shell(data))).unwrap()).unwrap();
+    // A group read emptied, as the packet writer marks it, takes picks the same way.
+    let mut tree = tree_of("<form1><page1><grains xfa:dataNode=\"dataGroup\"/></page1></form1>");
+    tree.apply(&DataOp::Value { path: path.clone(), text: "rye\nmillet".into() });
+    assert_eq!(tree.count(&path, "value"), 2);
+    // A node holding anything but `value` leaves is not a list's picks: it is left as it was,
+    // as the packet writer leaves it (and reports the skip).
+    for structured in [
+        "<form1><page1><grains><value>rye</value><note>x</note></grains></page1></form1>",
+        "<form1><page1><grains><value><b>rye</b></value></grains></page1></form1>",
+    ] {
+        let mut tree = tree_of(structured);
+        let before = tree.clone();
+        tree.apply(&DataOp::Value { path: path.clone(), text: "millet".into() });
+        assert_eq!(tree, before, "{structured}");
+    }
+}