Ok yall this is such a tough situation I’m in!!!

So a little back story I’m only 20 years old (almost 21 in a few months) now I have a 1.5 year old and a 6 month old and then I’m 16 weeks pregnant! Now don’t get me wrong it’s hard but I wouldn’t trade it and I do have family help! Now the issue is my fiancé (he’s 20) has a aunt (she’s only like 26 who had her kids in and out of foster care, now she’s not the worst person on earth she’s just not a good mom. She is way to angry and now has her 3 girls and about to get her other son back and she’s pregnant again🤦‍♀️ so this lady “spanks them, slaps them, bop them in the mouth and she’s just down right a b*** and she tells her kids all the time “don’t fcken touch me” and granted her two oldest are a lot as they have been in and out of dhs care and aren’t even potty trained at 4.. so we also have family on our side but I want to take the 2 oldest girls. I absolutely love them and care for them SOO much! And there mom is only focusing on the younger baby and the one she’s pregnant with, she lets these kids get hurt she doesn’t watch them and stays in the garage for hours smoking cigarettes while her kids are in alone. I got fed up tonight because while I was over having dinner (she’s living with my in laws) she went right to her bedroom and went to sleep while the kids had nasty diapers and were still up she just left them. So I got mad went in her room and said “dude I’ll just take your kids tonight since your not taking care of them” and she just nods and says thanks. Keep in mind I just had them for OVER a week because they bawl not to go home but they want to live with my fiancé and I and the girls:( we don’t want to call dhs on her because one we don’t want them to be separated, and 2 I’m not 21 till December so I can’t even foster them till then. And to make matters worse there dad just died in a car wreck soooo.. I mean it’s super rough because I’ll having them a couple weeks and get them on a amazing schedule and take care of them do the hair and just basic needs potty training and all then send them back to there mom for about a week or 2 and they come back my whole routine is gone and they act up (totally not there fault!!!) but it’s hard and my mom in law feels horrible to because that’s her sister but she also says the kids r better off somewhere else then with there mom so idk what to do 🤦‍♀️ and she’s about to get her son back 😞