But... if he is serious about this, then instead of custody he needs to go in and ask for a change in visitation. He will need to get a lawyer and go for 50/50 shared parenting time with his daughter. He has a much better chance of getting the extra time and then he can go from there as far as custody in the future.
I know with my sons our visitation is set up that I have him Sun-Wed... dad gets him Wed. -Sat. It works out great for all of us!How do you get custody?he should take her to court. he needs to be able to prove that he is the father and that she is unfit. if he just says she does these things and she denies it it will be her word against his. maybe he can record a phone call our argument where she admits to wrong doing for proof in court