SS influence daughter

So my daughters father hasn't been in her life for the first almost 2 years of her life, shes 2 now, and he recently walked back into it.

He's going to start taking her for visits at his and his girlfriends house next week, his girlfriend has a 4 year old.

But I have some major concerns

Firstly, I dont let me daughter have too much screen time, whe gets a tablet/phone for a half hour a day. Her step sister I guess you could call her is allowed to play xbox all day, they've admitted to me that she plays it so much she wont even go to the bathroom, she just pees in her pants while she's playing. If theres a chance that she can play her game, she will not leave the house.

They dont play with her, they dont take her outside to play, and the child has like no toys.

They dont discipline her, she gets whatever she wants, and she can act however she wants with no consequences. If she dont listen, or throws a fit over the game, guess what? She can still sit and play the game all day.

She bullys my daughter, like she takes things from her and throws them on the ground, everytime she picks something up, her SS takes it from her, she pushes her down, and hurts her. My daughters father doesn't do anything about it.

Her SS threw a fit when my daughter was playing with her doll and her stroller, stuff I bought for my daughter, her SS wanted it, so she threw a fit, and took it from her, when my daughter got upset her father gave her something else. When my daughter took it back from her SS, her father took it from my daughter and gave it back to her SS. Like wtf.

They dont want to listen to her, so they just give her whatever she wants.

And they self diagnose her, apparently right now she has ADHD, and anxiety, and something else I dont remember, was she brought to the doctor? Nope.

I'm scared for my daughter going into that environment, because I dont want all the parenting I've done in her life time and all the rules I've set to be unraveled. My daughter is a very sweet girl, shes very quiet, and she listens, and she picks up after herself, and she loves to go outside, yes she has her bad days, but she is the complete opposite of her SS. I think when she starts going over there, and learning that she dont have to listen, and she can be mean and throw things and hit people and throw fits to get what she wants, she'll come home and start acting like how her SS does.

I'm also scared that shes going to be bullied all the time over there, I'm scared shes going to get hurt, and she will learn to hate herself because of how shes treated by her SS. I was bullied, and that's exactly what happened to me.

I'm scared her SS is going to be favorited. And I'm scared my daughter is going to get whatever she wants over there with no rules.

I have my daughter on rules, she goes to bed at the same time every night, she eats good food and has meals at close to the same time every day. They have NO structure over there. Her SS stays up until midnight all the time. I'm so scared for my daughter.