<human>: Summarize the given text in a few sentences.

Long story short, my parents are remarried with other kids, and really never put much effort into raising me after I was 10 years old. It was actually pretty rough and I've since had abandonment issues along with not being NEAR where I thought I would education wise. An example of the disfunction that is my parents is when I was 14 and again at 18, I desperately needed an emergency root canal (because I wasn't taken to the dentist when I said I needed to go) and nobody would pay for it/take me because "your [MOM/DAD] needs to cover it". One tooth ended up falling out and my bf at 18 payed for the other one... My parents are also NOT anywhere near the poverty line... 
Anyway... I have talked a little bit with my Dad before about him living with us and the plan being, instead of sending child support between each other, they send it to us. So I'm not worried about them all of sudden wanted to raise/care for/wanting my brother back... But they can't even send each other $$$ without a court order, how can we ensure they wouldn't leave us hanging? (Which they do with promises on a consistent basis, especially financial). I really don't want to rely on for $$$ at all, but my husband is in grad school, I, undergrad, and we have a 6 month old baby. I feel like it would be the only fair way to give my brother a decent life (his own room, decent clothes, etc.). 

Also how can we approach things like medical bills and unexpected expenses? Should we just be saving for that out of the monthly check?
<bot>: How do we not allow my parents to completely wash their hands of responsibility of my brother if my husband and I become his "parents"?