Index: /trunk/src/org/openstreetmap/josm/actions/UnGlueAction.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/actions/UnGlueAction.java	(revision 17204)
+++ /trunk/src/org/openstreetmap/josm/actions/UnGlueAction.java	(revision 17205)
@@ -23,4 +23,5 @@
 import org.openstreetmap.josm.command.AddCommand;
 import org.openstreetmap.josm.command.ChangeCommand;
+import org.openstreetmap.josm.command.ChangeMembersCommand;
 import org.openstreetmap.josm.command.ChangeNodesCommand;
 import org.openstreetmap.josm.command.Command;
@@ -298,5 +299,5 @@
      * @param cmds List of commands that will contain the new "add node" command
      * @param newNodes List of nodes that will contain the new node
-     * @return new way The modified way. Change command must be handled by the caller
+     * @return The modified list of way nodes. Change command must be handled by the caller
      */
     private static List<Node> modifyWay(Node originalNode, Way w, List<Command> cmds, List<Node> newNodes) {
@@ -332,5 +333,5 @@
                 continue;
             }
-            Relation newRel = new Relation(r);
+            List<RelationMember> newMembers = new ArrayList<>(r.getMembers());
             // loop backwards because we add or remove members, works also when nodes appear
             // multiple times in the same relation
@@ -341,14 +342,14 @@
                     continue;
                 for (Node n : newNodes) {
-                    newRel.addMember(i + 1, new RelationMember(rm.getRole(), n));
+                    newMembers.add(i + 1, new RelationMember(rm.getRole(), n));
                 }
                 if (ExistingBothNew.NEW == memberships) {
                     // remove old member
-                    newRel.removeMember(i);
+                    newMembers.remove(i);
                 }
                 changed = true;
             }
             if (changed) {
-                cmds.add(new ChangeCommand(r, newRel));
+                cmds.add(new ChangeMembersCommand(r, newMembers));
             }
         }
Index: /trunk/src/org/openstreetmap/josm/command/DeleteCommand.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/command/DeleteCommand.java	(revision 17204)
+++ /trunk/src/org/openstreetmap/josm/command/DeleteCommand.java	(revision 17205)
@@ -29,4 +29,5 @@
 import org.openstreetmap.josm.data.osm.PrimitiveData;
 import org.openstreetmap.josm.data.osm.Relation;
+import org.openstreetmap.josm.data.osm.RelationMember;
 import org.openstreetmap.josm.data.osm.RelationToChildReference;
 import org.openstreetmap.josm.data.osm.Way;
@@ -307,5 +308,5 @@
         if (!silent && !callback.checkAndConfirmOutlyingDelete(parents, null))
             return null;
-        return new DeleteCommand(parents.iterator().next().getDataSet(), parents);
+        return new DeleteCommand(parents);
     }
 
@@ -457,7 +458,7 @@
                 .collect(Collectors.toSet());
         for (Relation cur : relationsToBeChanged) {
-            Relation rel = new Relation(cur);
-            rel.removeMembersFor(primitivesToDelete);
-            cmds.add(new ChangeCommand(cur, rel));
+            List<RelationMember> newMembers = cur.getMembers();
+            cur.getMembersFor(primitivesToDelete).forEach(newMembers::remove);
+            cmds.add(new ChangeMembersCommand(cur, newMembers));
         }
 
@@ -465,5 +466,5 @@
         //
         if (!primitivesToDelete.isEmpty()) {
-            cmds.add(new DeleteCommand(primitivesToDelete.iterator().next().getDataSet(), primitivesToDelete));
+            cmds.add(new DeleteCommand(primitivesToDelete));
         }