[otrs] Related tickets?

I could swear that there was a way to have linked tickets in OTRS, but I'm not finding it at the moment. Is there one, or am I just mixing it up with something else ...? Also, when one is using the customer front end. Is there a way to make it so that a customer sees all tickets that have their customer id on them, whichever queue they are in? The problem I am having is that if a ticket comes into the customer queue and I reassign it to another group then the customer can't see it any more. thanks :) paul