Dirty kids

If you dont want to read this whole rant, skip to the last paragraph, but this is here so i dont look like a downright horrible person.

So i have a neice and nephew who are always dirty. The oldest, 5, has the BO of a 12 y/o boy in gym class. My neice is 4 and still wears diapers and her mother doesnt even try to coax her into potty training and instead lets her just pee all over the mattress she sleeps on that we bought.

I dont want to just break my sister in laws heart, but she literally has no idea that i go to the same school as those children and i try to pretend i dont. its a small town i honestly shouldnt have to be embarrassed to say theyre my family because Im surprised CPS hasnt been called.

She is a stay at home mom and my brother works hard, even THEY are both unclean people. Everything weve given them that is small, or not a dire need of hers, is lost in the abyss of her car. Her car reeks of spoiled milk and mildew.

For example the youngest was on the last stage of baby food and she cleaned out her car and found plenty of half empty BOTTLES.

They were married young because they got pregnant but theres nothing wrong with their marriage, they just act like they dont want to put any work into parenthood because ‘theyre too young to be in this position anyway’ like they didnt deserve to lose their young free lifestyles. Or thats how their attitude seems considering that they drop their children off at our house every saturday night and then go get wasted. Anyway besides the fact that they arent good examples, i cant change that, their kids are SO DIRTY.

My neice i think has some sort of infection in her bladder from sitting in wet underwear too long because her pee has such a strong sickening odor. And trust me its ruined upholstery in their house and ours. Its not that poor babys fault im sure. When theyre at our house we make certain she goes potty regularly, but we cant guarantee that at home.

Wow so many examples need i go on?

Oh one more, my other brothers girlfriend saw my neices hair was severly tangled and tied up in a ponytail and she went to brush it out for her and there was like a three day old wad of gum in her hair and they had to cut it out because my SIL had just continued to throw it up in a pony tail without brushing it. She probably didnt even know it was there. If she did she wouldnt have done anything either though.

Is there anything i can do to let her know this isnt okay that wont entirely crush her spirit or make her blackmail me or something(shes very confrontational and she loves a good fight)? These kids are dirty and they are literaly going to get made fun of when the next one goes to school next year. Im just so annoyed and ive had to bite my tongue for 6 years. I am tired of these kids thinking i am the mean aunt for making them take baths and wash behind their ears. Please help.