The father has joint legal custody of both boys
Thank you for the additional information.
Legally the mothers can not prevent the father from seeing the children. Allegations alone are not sufficient. If the mothers wanted to stop the visitation then they would need to go back to court and file a modification petition seeking a limitation in the access the father has with the children. The mother's are actually in contempt/violation of a court order at this point and the father can force visitation until the mothers formally seek a change in court.
If the mothers do seek the change they would have to convince the judge that such sexual abuse did happen.
They are not limiting his access, but not allowing him to have the boys at the same time. Can they dictate whether or not he has them at the same time?
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