Hello,
As long as Group with id=1 is a pre-existing Group object your code with the merge should work as expected. The code Markus provided is a better approach but your code should still work. If the issue continues please file a Glassfish issue and supply a simple testcase.
--Gordon
[Message sent by forum member 'gyorke' (gyorke)]
http://forums.java.net/jive/thread.jspa?messageID=204107