Need advice “baby mama drama”

Just want to start off by saying I’m not looking for any negative feedback just advice.

My sister says I shouldn’t get in it and I don’t for the most part, all I do is give my husband advice sometimes he takes it sometimes he doesn’t.

He has a 6year old daughter with his ex wife. His daughter lives with us Sunday-Friday. She picks up her daughter when it’s convenient for her. She always says she’s sick but post on social media sites out for dinner, concerts, out shopping, etc. She picks up her daughter without a booster and my husband has offered countless to buy her a booster but she denies and claims she has one but every time she picks up their daughters she straps her in one. She doesn’t show up for a lot of her daughters events such as (karate classes, school events, teacher meetings). She has 3 other kids so we give her the benefit of doubt but she’s picked up their daughter with the car smelling like weed and everyone looks stoned. Her kids post videos and pictures of them smoking weed all over social media.

The list just goes on. She never showers her when she’s there, she doesn’t have her brush her teeth (for the longest time approximately 6-7 months she didn’t even have a toothbrush and we offered to buy her one and she declined). She doesn’t brush her hair and she has really long hair. All she feeds her is spaghetti and microwaved hotdogs or gives her candy. She won’t pick her up 2-3 weeks at a time sometimes and just tries to buy her love by buying her candy, toys or whatever any 6year old wants. I don’t know what to say anymore, we feel hopeless.

Now with all this going around with the virus, our state has shut down schools, basically everything and is encouraging social distancing and she sets up a play date on the day she’s supposed to drop her off to us and schedules a sleepover with kids that always give her daughter head lice. Which when she comes back home I spend hours going through her hair trying to get rid of.

Update:

We have her 85% of the time, we don’t want to open up a can of worms and potentially the judge deciding In 50/50. She voluntarily agreed for their daughter to live with him after there divorce. Their divorce papers states she gets her 3 days then he gets her 3 and they switch back and forth on Sunday’s but she never followed that and doesn’t give her $200per month in child support either. However lately she’s been sending him randomly $100 here and there (we think she’s afraid of being taken to court). They’ve been divorced for 2-3 years now.

What would you do if you were in my shoes