Maybe moving, helping me.

My brother in law wants my husband and I to move in to his house with him and his wife. My brother in law can no longer afford his house and bills since his wife stopped working. We have 2kids and I’m pregnant again so there will be a 3rd. We only live in a 2bedroom home that we own, but it’s not gonna be big enough for all of us. My brother in law home is a 3bedroom, plus a finished basement. So it is bigger than ours now. They want to give us the top half, and they live in the basement, only sharing the kitchen and bathroom as needed until they put a bathroom and kitchen downstairs. I don’t care for his wife, and she doesn’t like me either. We would get money from moving out of our house, not a lot since it’s a trailer in a trailer park, but the park will give me $4-5k and moving in with them our bills will be less and We will be able to save money for a new house. What would you do? Pros and cons on sharing a house with your in laws?