Should the father have custody of child?

My b-friend’s ex has custody of their 10 yo girl. She works from 2-10 p.m. with 2 days off during the weekday & for the past 2 years has used this as an excuse during school time for not being able to get her up and ready for school so my b-friend and I have. The mother has to be responsible for her 1 day out of the week and usually don’t send her to school this day or she is late. He pays $253 month child support and has her 90% of the time. She never attends ball games or conferences or does anything with her. She gets Thurs. and Fri. off work and is usually still in bed when she gets home from school and sleeps probably 16 hours a day, no lie. Now this year she is telling her daughter that she won’t be coming to our house as much while school is in and in fact will be responsible for herself there and needs to set her own alarm, fix her own breakfast, and get to the bus stop by herself while the mother stays in bed. Would this alone be grounds to file for custody?
By the way, her father does work and still takes care of things and I work 2 jobs and do more for her than her mother does. Us living together without being married does not make us bad parents, sleeping for 16 hours a day when you have 2 children (one of her kids is 3) makes you a bad parent.
Even with our busy schedule and another child in the home we have attended every conference, every ball game, every little concert, etc. She has been to 1 ball game in 3 seasons and 1 conference since she started school.
We’ve been together 7 years. He works and I work 2 jobs. Neither of us have any jail records or any bad pasts. This mother also takes Lunesta sleeping pills to keep herself asleep this long. I’m not the girlfriend of the month, I’m practically her mother as her own mother is TOO lazy to be one.
Oh this is so my business as long as the mother keeps sending her to my house and I am helping take care of her so comments like it’s none of my business are not necessary because she is my business. I am being there for her when her own mother is not, physically, emotionally, etc.

See a lawyer. Take notes of what is happening. Sounds like you are doing a good job. At 10 years old she cannot be expected to look after herself. And going to the bus stop herself???? Safety springs to mind what is this stupid cow thinking. She is not fit to look after the child start the ball rolling straightaway. At the end of the day her welfare and safety come first not the mothers fellings.