Max9 inserted files in Documents lost after Transfer

I'm using Maximizer 9 and have to update/synchronize two address books. Here is what I do in steps:
1. in book A, select all address book entries
2. klick on Transfer, Address Book Entries, Transfer Method "Direct Addressbook access"
3. I select all transfer options and use "record modify flag" and "reset record modify flag", the "overwright duplicates" option is left unselected.

The Documents (inserted as file, no link) in Book A are not transfered to Book B.
If I add the "Overwright Duplicates" option, the Documents from Book A are transfered, but then the old Documents in Book B are gone.

I tried several other combinations of the transfer options but nothing worked. What am I doing wrong? I found nothing in the documentation. I appreciate any HELP. Greetings from Germany