Legal Question in Family Law in Washington

Unless you signed something giving your mother third party custody of the children, theoretically, you can just go pick them up from wherever they are. If they are with your mother all the time, you could try calling the police, and they will come out. Sometimes the police will tell you there is nothing they can do and that you will need to go to court to force your mother to give you the children. Other times, the police will tell your mother that so long as there is no court order barring you from taking custody of your own children, that your mother is required to hand them over.

You could also file a police complaint for custodial interference in the second degree under RCW 9A.40.070(1), which provides, that if your mother retains, detains, or conceals your child with the intent to deny you access to your child, and you have a lawful right to physical custody of your child, then your mother is guilty of custodial interference. That will at least force the police to call and investigate the complaint.

I suggest you hire local counsel to help you out, but in case you cannot get someone due to the cost, then try the Northwest Justice Project, or your local county bar association to see if they can recommend someone to help you out.