No attorney - in this forum or otherwise - can advise you to use threats to obtain settlement in any proceeding, and it would be especially true in a custody proceeding where the interests of the child may not be represented.  Thank goodness the court has final approval of matters in the best interests of the children.  If you want to know what your options are with regard to your assets - here real property and not the children - then yes, partition actions can be used to force a non-compliant co-owner to sell, as the court generally does not split the house in half but orders a sale to split the proceeds.  As for the children and custody, just contest his or her stand on the matter and appeal to the Judge based upon your love for your children.  And get a lawyer.