Difference between helping out and taking advantage?

When it comes to helping out a family member where does the line get drawn? Won't it be logical to draw the ground rules in the beginning? My living situation is not very pleasant, my brother in law lives with us and my husband and I argue because, I feel like he is taking advantage and my husband feels like its not a big deal because that is his brother. I would not play favoritism if it were my siblings and I would ask them to leave. I can't talk to my husband period because he just 'doesnt want to talk about it' and he has already more than once asked his brothert to keep up with his stuff and so on. . . How far is too far? My husband and I both work and have two kids, I also am going to school. His brother, all he does is go to school and play video games and sleeps. Now common courtious people would offer to help out with anything, not this guy or should I say grown man. He doesn't help but only when asked it drives me insane!!! Help me out please!