How to deal with my gf brother

This my burner account. My girlfriend (26F) and I (28M) have been together for about 1 year. We're looking for a new apartment/home to move into. She's got a brother (22M) that's coming with us since we all have been living together for about 7 months, and before I joined them, it was them 2 for a few years. The thing is, after living with them for 7 months, I have noticed brother does not pick up after himself or his girlfriend or his dog AT ALL. Im talking 0 contribution to the house. It's always been this way my gf tells me. This new places we're looking at, they're more expensive, but brother is actually gonna be paying less than he pays now for rent so that he can save and hopefully move with his girlfriend in the near future. I believe I am being very considerate towards him and what my gf wants for him. (Gf said no matter what, our apartment will always have doors and room open for him because that's his baby brother) - So our apartment must have an extra room for him at all times just in case, and while he's with us his contribution is close to nothing. The only thing I will be asking before we move in is that brother needs to be cleaner and pick up after himself, help around the house, and if his girlfriend is coming over and starts using the washer and dryer and taking showers, they need to chip in more. Question 1 is, am I being too considerate? I'm doing this for my girlfriend because they have a close relationship, but I couldn't live with him for more than 1 year. He's inconsiderate in many ways. Question 2, how can we this conversation without turning into a brawl? Any tips on dealing with this situation is appreciated. Everyone is a little bit of a hothead in the household