Eligible couples must share a common residence. They cannot be closely related, married, or in a domestic partnership with another person.You will learn how a Living Together Contract (an LTC) works, if it makes sense for your situation, other options you may have, and where you can learn more. Gov phone: 360-725-0377 option 3. General information and self-help packets about family law issues for unmarried couples in Washington state. You will first need to follow a number of Department of State procedures to add your spouse, partner or child to your orders. Only domestic partnerships not documented in a state registry must complete this affidavit. Information Provided: This affidavit typically includes the affiant's full legal name, date of birth, and their current residential address. Laws of the State of Washington. It used to be called apaternity acknowledgmentorpaternity affidavit.