Hi Egon,
One option available is Linked Sql Server where you can issue distributed query. You will have to update your sync commands set for the dbsyncprovider accordingly. This option may however take some performance hit. The second link below
will give you some tips and guidelines to keep performance in check.
http://msdn.microsoft.com/en-us/library/aa213778(SQL.80).aspx
http://www.sql-server-performance.com/tips/linked_server_p1.aspx
If you are ok with same database but different namespace(schema name) will address your concern then this would be better option.
Thanks
Jandeep
jandeepc