So he had a son from a previous marriage. She has a few of her own from previous relationships. They’ve faced fertility issues and now have the go ahead from the doc that after an expensive surgery on her uterus that they can try for their own. 
The son has been abused before dad had custody and faces issues that he obviously needs therapy for. The whole family (including FIL) taunt and bully the poor kid. The step siblings are vicious. He escaped one abusive situation for a whole new one. I don’t blame the kid for wanting to avoid them and be in his own world. 
BIL and SIL are into drugs (the life ruining kind) and think that medical marijuana is the cure for everything.  She doesn’t believe in therapy or modern medicine (anti vaxx).  He’s got anger issues and problems from his own father being abusive - ones his wife won’t allow him to get therapy for or take meds. He can be scary when upset or high and has threatened to kill family members. 
I haven’t expressed these opinions with my husband (BIL’s brother). But I just don’t see why they should bring another kid into the world if they can’t even properly treat the kid who badly needs help.  Or think it’s okay to do drugs an act like they aren’t in their thirties and parents. 
Also they can’t afford the surgery (which I get - insurance where we live is shit in general for women who want to have babies) but my husband and I have bailed out other family members financially because they just choose to make shitty decisions. Legit shit decisions and feel like they’re entitled to our money to fix it.  She started a online fund and pushing the whole “Christmas is for giving” line. 
I just can’t tell if I’m a monster for thinking maybe it’s not the best choice to bring a baby into that mess. I feel terrible for her fertility issues and wouldn’t wish them on anyone, but...I worry for that child’s future well being. 