I agree with Davy. If the process has been started in court, it is absolutely a very bad idea for Dad to show up and remove the children. It is not just a matter of Mom having "status quo", the children are now residents of another state. While that state won't have jurisdiction, you cannot simply show up and remove them from that state and take them across state lines. Opens the door for a whole lot of problems if done. Dad unfortunately has to rely on the court system and the process.