custody arrangement

on paper it's 50/50 legal and is 44/56 physical custody. But in reality we have my OHs child more than 44% of the time it's actually 50/50. we found out my OHs daughter doesn't want to go to mom's house, she lives with family, because she isn't there ever but maybe one day a week during her time and it's not due to work at all. his daughter has a sibling as well from another guy that is feeling the same way. they only want to go if mom is there and not any other time. we also found out mom isn't sleeping there when she has the kids during her time. So her family is the one carring for them when she just doesn't come home and the one day she is there she puts them to bed and then leaves. we have tried for a while to get my OHs daughter to just be ok with going over and spending time there but she is now becoming angry at mom for never being there and just doesn't want to go. should we still force her to go even thought she doesn't want to and her mom isn't even there to care for her. there is first right of refusal in the custody order. and both father's are looking at changing the custody agreement since she only wants to see her kids about 4 days a month by choice when she has 50/50 for both of them.