The management of users is outside of jboss. You simply add them to the ldap and jdbc stores. The only intersection occurs if you change users with active sessions and you want the change propagated immeadiately in which case your admin op needs to flush the jaas cache as described on the wiki.
Flushing cache will lead client to re-login. So, the client application should correctly handle the situation, when during any business call it can get the request for re-authentication.