route.all-resources when another resource comes online?

hi there...

i have some kind of a tricky question: i can set the property "route.all-devices" to true - ok. but what if a user is online with two resources and logs in with a third device after a little while. is it somehow possible, that the message, that have been routed to the two ressources, will be routed to the third resource subsequently?

any help would be appreciated

thanx