So the lawyer answered about the window being closed to getting the kids back in state, but then the lawyer doesn't tell them they need a new parenting plan in order to ensure they will be able to continue to see the kids.
I would file for a refised parenting plan (in their state) that specified when the kids had to travel to see the dad, exactly when phone calls would happen (phone visits) and that she is responsible for all the travel expenses (in WA this part has to be in the child support order) or file the custody order with a new child support order that gives full credit off the child support for the travel expanses. Have mom served and see what happens from there.