While custody order is pending, what is recourse

I’m about to file a custody claim (per my prior post). In the event that this makes my ex mad, and he takes and refuses to return the child(ren) would I have any recourse while the claim is pending?

If he withholds the children, you could use his actions against him when you get in front of a judge, but in the interim, since there is no order in place, either of you has every right to have custody of the children.