Just to put a bit more bones on that What if she was your kid. (You obviously don't think of her as yours)
I've brought 2 girls up and unless other dads have experience of it they dont understand the difficulties involved in being a stepdad. Its the most frustrating situation you can ever find yourself in.
my 10 bobs worth my daughters step **** was fine until he married the fat slag(daughters mum). then he seemed to think he was the daddy.i could understand it if i wasn't there for my daughter.dunno if thats the case with the little pole dancer. my birds youngest is the biggest bitch on the planet until she wants something or wants to impress her latest boyfriend.tried being there for her coz her dad isn't but it doesn't work. understandably our lass takes her side no matter what.just glad i had the good sense not to move in with them so walking away is a much used option.