The issue of carnets is this,
Officially
If the chica visits, the casa owner is responsible for registering her. If he gets caught not registering, then it might cost him a $500 fine. You might work out a deal with the casa owner where he gets the carnet but does not register it. He gets protection and it also makes the chica think twice about stealing stuff (yours and the casas) as she cannot get out without her carnet.
The other issue, is that the chica does not want to be registered. If she is registered with two extranjeros, she is a puta and eligible for residency in the crowbar motel.
Keep your shit locked up in a suitcase or something.
