QUESTION: if someone's name is on the lease to my house and they are over seas for a year. Should…

QUESTION: if someone's name is on the lease to my house and they are over seas for a year. Should they still be able to use the house for whatever they want ie:storage if they don't pay anything on the house. My mom is on the lease also and doesn't consider it her house and she doesn't help pay it off. She's just on it to help me get a loan. This is ridiculous. I always have an issue with my brother. He's such an ass sometimes. The room he wants to use is planning to be used for my bfs son who is about to move in and at last minute he says something like this. It's not his damn house. Always something with him