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FL All Family 119Mandatory

Agreement to Join Petition (Joinder)

Washington · Washington State Courts · Effective May 1, 2016

This form is an agreement that allows a person to join a case that another person started. By signing it, the person agrees to the requests in the other person's filing, unless they file a separate response before the court makes final orders.

Open the official PDFfrom Washington State Courts

Where this fits in a case

Start a case

Stage: Start a case

This form is used in family law cases when a person wishes to join a case that has already been started by another party.

Either party may file.

Common questions

What is this form for?
This form is an Agreement to Join Petition, which means it lets you agree to join a case that someone else started. It asks you to agree to the requests in the other person's filing.
What happens if I sign this?
If you fill out and sign this, the court might approve the requests listed in the Petition, unless you file and serve a Response before the court signs final orders.
Do I have to update other forms?
If this case involves parentage or child support, you must also update your Confidential Information form (FL All Family 001) if you use this form.

Revision history

No changes recorded since we started tracking this form on October 9, 2026. The current version took effect May 1, 2016.

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