Can my husband modify custody?

My husband has two 4 year old boys. He has joint legal custody and a set visitation schedule. The divorce between him and his ex was just finalized in December, since then she has tried to deny him his spring break visitation, that thankfully was resolved through her lawyer who told her she had to comply, and now she has denied him his two weeks this summer. She wouldn't pay her portion of the transportation costs which are rather high because she moved to florida with the children and my husband and I live in WA. She also refuses to share information about their daycare and doctor. She has no interest in co-parenting these children and she is violating the court order already. During the divorce she tried to disappear with the children, and the judge urged her to comply with the order. My husband is filing contempt charges for the denied visitation and her failure to share information with him concerning the children. Can custody be modified because of this? She has told him more then once in front of the children, myself, and their aunt that he is nothing to HER children. I feel awful for my husband, but we are both worried about the boys....