diff -r ff8ad2c9e1bd -r ec1f2015ec79 src/cx/tree.h
--- a/src/cx/tree.h	Sun Oct 06 19:02:32 2024 +0200
+++ b/src/cx/tree.h	Sun Oct 06 19:17:41 2024 +0200
@@ -1157,8 +1157,29 @@
 }
 
 /**
+ * Sets the (new) parent of the specified child.
+ *
+ * If the \p child is not already member of the tree, this function behaves
+ * as #cxTreeAddChildNode().
+ *
+ * @param tree the tree
+ * @param parent the (new) parent of the child
+ * @param child the node to add
+ * @see cxTreeAddChildNode()
+ */
+__attribute__((__nonnull__))
+void cxTreeSetParent(
+        CxTree *tree,
+        void *parent,
+        void *child
+);
+
+/**
  * Adds a new node to the tree.
  *
+ * If the \p child is already member of the tree, the behavior is undefined.
+ * Use #cxTreeSetParent() if you want to move a subtree to another location.
+ *
  * \attention The node may be externally created, but MUST obey the same rules
  * as if it was created by the tree itself with #cxTreeAddChild() (e.g. use
  * the same allocator).
@@ -1166,15 +1187,14 @@
  * @param tree the tree
  * @param parent the parent of the node to add
  * @param child the node to add
+ * @see cxTreeSetParent()
  */
 __attribute__((__nonnull__))
-static inline void cxTreeAddChildNode(
+void cxTreeAddChildNode(
         CxTree *tree,
         void *parent,
-        void *child) {
-    cx_tree_link(parent, child, cx_tree_node_layout(tree));
-    tree->size++;
-}
+        void *child
+);
 
 /**
  * Creates a new node and adds it to the tree.