I have legal custody and full primary placement but the father is objecting

   The answer to your question in part, depends on where you are with your case. If there never has been a final custody and placement order, than it changes the playing field on what his chances might be or what he can argue in terms of either getting primary placement or shared or equal placement. If custody and placement are finalized, there is a two year law in Wisconsin that bars him from asking the court (or you) to modify custody and placement, unless it can be shown that the child is imminent harm. After two years from the final orders, the burden is less, but he would still need a substantial and compelling reason why he is asking to modify the existing court orders and there is a presumption that things should be left as is. The court will appoint a guaridan ad litem to advocate for your children's best interest, and given his history, no matter where you are in the court proceedings, in my opinion, his chances do not appear good. No one can offer you any guarantees or promises. It would be best to sit down with a family lawyer of your choice to discuss your case, what your respective chances might be, the cost of litigation and how long such a battle might take.