problem with stepdaughter and lice

[alexis34]

I have been with my husband for 6 years with 3 out of the 6 married. Since day one with my stepdaughter she has had lice everyweekend we have gotten her. We went to court to try and get custody of her and lost. we brought up the lice ordeal and they said it was not an issue or considered a health hazard. For 6 six? Not an issue? We are now seperated and getting a divorce. We have a 2 years old together, now when she comes back from her dads she has lice. She has had it 3 times now in two months. What legally can i do to keep her from going to his house and getting this. I cant put my child what the 7 year old has gone through for 6 years of her life every other weekend!!!! Please help if there is any!!!