Does anyone know what age the child gets to choose what parent they want to live with?

Thank you all for your comments, especially the pirate ship. Made me laugh!

I honestly don't know if I want SD12 to be able to choose and don't know exactly what she would choose if she could. I think she'll try flipping between the houses. Right now her father and I are only dating, but have discussed getting married. I am much more strict then he is, pay more attention to things like bad manners, grades, etc. He's getting better, but, man is it a tough nail to hammer into his head. If we were to get married, they would be moving into MY house (to become OUR house), but I would definitely have a hand in rules, consequences, and chores.

Earlier in our relationship he asked me to help him "parent" his child because her mom was such a crazy flake. He wanted her to grow up like me. I was raised by a single mom and have a lot of her same ideas. After a short time, he asked me to back off because I would really get on SD12 for lying. Told her I didn't believe her all the time. OK...so really, you don't want my help. I step back.

Well...yesterday they show up at my house. He's livid. I had recently gave her a razor to shave her underarms (discussed with him first!) and she used it to shave her legs. When she cut herself, she told him that the cat had scratched her. He comes home to a bloody towel on the bathroom floor, asks her repeatedly if she's sure the cat scratched her. Finally makes her show him her leg where he can tell she shaved them (duh!). Over to my house they come, he tells her to go into the room she uses at my house and write up 10 things for punishment. To name a few she came up with: punch her in the face (what?!), treat her like a dog, make her eat dog food, sleep in garbage, don't believe her.

Okay, well that last one is fact, not a punishment. Literally the only thing on the list of 10 that wasn't demeaning or ridiculous was "take away my TV and Wii". I'm looking at the list and telling SO, you need to go talk to her about this! He does, and there's crying. Apparently (taken with a grain of salt from the liar) BM has been telling her to lie to SO for quite some time. NOT that gives her an excuse for lying to him yesterday, she knows the difference. However, she's learning from her mom that lying is OK. SO and I both think that she needs some counseling. BM, from SO and SD12 sounds like she is really unstable. Came into SD12's room last week while she was sleeping and started yelling that nobody respects her.

I feel sorry for this kid. I do. At the same time...I feel sorry for me. Yes, SO is finally doing some parenting, but really, he's to blame for her still lying to him. SD12 would stop lying to him if there were consequences for her lying to him. We've been together over a year and I would say this is the second time I've ever seen her have consequences for lying.