How do I decide to have kids with a man that has children with two other mothers?

He has a son (11) that has 4 other siblings with 3 other fathers. He has a daughter (5) that has 3 siblings by at least 2 other fathers. I'm debating about bringing child into the world that will have to deal with their brother and sister having to leave every so many days to go to their mom's. They would also have to share in the frustrating problems these mothers cause because of their selfishness and lack of care for their children's best interests. I love this man very much and really want to have children, but I don't know if I should stay with him if I decide that I don't want to have to deal with everything that his past life will cause.