And how are you "choosing them"?
Once you have added table occurrences in Manage | Database | relationships with a remote data source reference to a table in another file, you can access that table just as though it was defined in your current file. The same rules apply however, so you need to set up a layout based on the table occurrence if you want to edit the records directly. Or you can link the occurrence to a different occurrence and access that data via a portal from a layout based on the now linked table occurrence. (But this requires match fields with matching values.)
Thanx alot! Thats what I though, but i was allways looking fo some Italic signed table name, i just went trough the normal ones and since the name was so simular, i just did not see it ;)