Ex husband warned not to come to property but he insist using pick up children as excuse, can I charge him trepass? WA state

Do you have it documented such as a PFA? Do you have a custody order? If noty ou need to get one and stipulate in it when and where visitation pick ups will take place.

Coming "to" the property is not trespass. Entering the house or yard might be. But I doubt if a prosecutor will prosecute since this is a civil issue.

What you need to do is get visitation set up so that you turn over the children at a neutral location. Then, if he shows up at the house, you can have him cited for contempt of court.