A further Object Aquiring Issue

I have some hierarchical ZMS-Nodes for testing with default contents in
them.

ZMS_A > ZMS_B > ZMS_C

If I let a sub node aquire object classes(com.zms.foundation) from
above, a lot of attributes of the already existing content break (Attrs
of the ZMS node itself, titles of folders, ...).

I have to export com.zms.foundation from a parent node, deaktivate all
these objs in the parent node, import the export.metaobj.xml file into
the subnode with the broken contents and activate the objs in the parent
node again to get this repaired.

The problem is, if ZMS behaves in this way, it is not possible to aquire
existing objects from above if content is already present. Why is that
so?

Regards
Peter Zechmeister, JKU