diff --git a/doc/susp_aaip_isofs_names.txt b/doc/susp_aaip_isofs_names.txt
index 59217a6..ecff23a 100644
--- a/doc/susp_aaip_isofs_names.txt
+++ b/doc/susp_aaip_isofs_names.txt
@@ -22,6 +22,8 @@ Purpose:
       END is also the block address of the start of the checksum recording
       area in the image.
       See also isofs.cx .
+      This attribute shall eventually be attached to the root directory entry
+      and be global for the whole image.
 
 Format of Value:
       START_LEN | START_BYTES | END_LEN | END_BYTES |
@@ -150,7 +152,7 @@ Registered:
 -------------------------------------------------------------------------------
 
 This text is under
-Copyright (c) 2009 - 2010 Thomas Schmitt <scdbackup@gmx.net>
+Copyright (c) 2009 - 2011 Thomas Schmitt <scdbackup@gmx.net>
 It shall only be modified in sync with libisofs and other software which
 makes use of AAIP. Please mail change requests to mailing list
 <libburn-hackers@pykix.org> or to the copyright holder in private.
diff --git a/libisofs/libisofs.h b/libisofs/libisofs.h
index 3f8a45a..52844c8 100644
--- a/libisofs/libisofs.h
+++ b/libisofs/libisofs.h
@@ -4649,11 +4649,18 @@ int iso_tree_add_new_cut_out_node(IsoImage *image, IsoDir *parent,
  * @param new_parent
  *      The existing directory node where to insert the cloned node.
  * @param new_name
- *      The name for the cloned node. It must not yet exist in new_parent.
+ *      The name for the cloned node. It must not yet exist in new_parent,
+ *      unless it is a directory and node is a directory and flag bit0 is set.
  * @param new_node
- *      Will return a reference to the newly created clone.
+ *      Will return a pointer (without reference) to the newly created clone.
  * @param flag
- *      Unused yet. Submit 0.
+ *      Bitfield for control purposes. Submit any undefined bits as 0.
+ *      bit0= Merge directories rather than returning ISO_NODE_NAME_NOT_UNIQUE.
+ *            This will not allow to overwrite any existing node.
+ *            Attributes of existing directories will not be overwritten.
+ * @return
+ *      <0 means error, 1 = new node created,
+ *      2 = if flag bit0 is set: new_node is a directory which already existed.
  *
  * @since 1.0.2
  */
diff --git a/libisofs/messages.c b/libisofs/messages.c
index 7326246..13a9442 100644
--- a/libisofs/messages.c
+++ b/libisofs/messages.c
@@ -97,6 +97,8 @@ int iso_node_xinfo_make_clonable(iso_node_xinfo_func proc,
 {
     struct iso_xinfo_cloner_assoc *assoc;
 
+    /* >>> look for existing assoc of proc */;
+
     assoc = calloc(1, sizeof(struct iso_xinfo_cloner_assoc));
     if (assoc == NULL)
         return ISO_OUT_OF_MEM;
diff --git a/libisofs/tree.c b/libisofs/tree.c
index 4035439..46b66d3 100644
--- a/libisofs/tree.c
+++ b/libisofs/tree.c
@@ -1015,6 +1015,9 @@ int iso_tree_copy_node_attr(IsoNode *old_node, IsoNode *new_node, int flag)
     return ISO_SUCCESS;
 }
 
+/*
+  @param flag bit0= merge directory with *new_node
+*/
 static
 int iso_tree_clone_dir(IsoDir *old_dir,
                        IsoDir *new_parent, char *new_name, IsoNode **new_node,
@@ -1025,12 +1028,15 @@ int iso_tree_clone_dir(IsoDir *old_dir,
     IsoDirIter *iter = NULL;
     int ret;
 
-    *new_node = NULL;
-
-    ret = iso_tree_add_new_dir(new_parent, new_name, &new_dir);
-    if (ret < 0)
-        return ret;
-    /* Avoid early grafting of directory to allow cloning of old_dir to a
+    if (flag & 1) {
+        new_dir = (IsoDir *) *new_node;
+    } else {
+        *new_node = NULL;
+        ret = iso_tree_add_new_dir(new_parent, new_name, &new_dir);
+        if (ret < 0)
+           return ret;
+    }
+    /* Avoid traversal of target directory to allow cloning of old_dir to a
        subordinate of old_dir.
     */
     iso_node_take((IsoNode *) new_dir);
@@ -1043,24 +1049,30 @@ int iso_tree_clone_dir(IsoDir *old_dir,
         if (ret == 0)
     break;
         ret = iso_tree_clone(sub_node, new_dir, sub_node->name, &new_sub_node,
-                             0);
+                             flag & 1);
         if (ret < 0)
             goto ex;
     }
 
-    /* Now really graft in the new tree */
+    /* Now graft in the new tree resp. graft back the merged tree */
     ret = iso_dir_add_node(new_parent, (IsoNode *) new_dir, 0);
     if (ret < 0)
         goto ex;
 
-    *new_node = (IsoNode *) new_dir;
+    if (!(flag & 1))
+        *new_node = (IsoNode *) new_dir;
     ret = ISO_SUCCESS;
 ex:;
     if (iter != NULL)
         iso_dir_iter_free(iter);
     if (ret < 0 && new_dir != NULL) {
-        iso_node_remove_tree((IsoNode *) new_dir, NULL);
-        *new_node = NULL;
+	if (flag & 1) {
+            /* graft back the merged tree (eventually with half copy) */
+            iso_dir_add_node(new_parent, (IsoNode *) new_dir, 0);
+        } else {
+            iso_node_remove_tree((IsoNode *) new_dir, NULL);
+            *new_node = NULL;
+        }
     }
     return ret;
 }
@@ -1141,12 +1153,18 @@ int iso_tree_clone(IsoNode *node,
 {
     int ret = ISO_SUCCESS;
 
-    if (iso_dir_get_node(new_parent, new_name, NULL) == 1)
-        return ISO_NODE_NAME_NOT_UNIQUE;
+    if (iso_dir_get_node(new_parent, new_name, new_node) == 1) {
+        if (! (node->type == LIBISO_DIR && (*new_node)->type == LIBISO_DIR &&
+               (flag & 1))) {
+            *new_node = NULL;
+            return ISO_NODE_NAME_NOT_UNIQUE;
+        }
+    } else
+        flag &= ~1;
 
     if (node->type == LIBISO_DIR) {
         ret = iso_tree_clone_dir((IsoDir *) node, new_parent, new_name,
-                                 new_node, 0);
+                                 new_node, flag & 1);
     } else if (node->type == LIBISO_FILE) {
         ret = iso_tree_clone_file((IsoFile *) node, new_parent, new_name, 
                                   new_node, 0);
@@ -1161,6 +1179,8 @@ int iso_tree_clone(IsoNode *node,
     }
     if (ret < 0)
         return ret;
+    if (flag & 1)
+        return 2; /* merged two directories, *new_node is not new */
     ret = iso_tree_copy_node_attr(node, *new_node, 0);
     return ret;
 }