Uniform Parentage Act. (RCW 26.026) Act defining parent and child relationship under the Revised Code of Washington. Under the UPA, paternity can be established under a court order, or presumed to exist under specified circumstances. A man is presumed to be a child's father when: He receives the child into his home and openly holds out the child as his own; His mane is on the child's birth certificate issued by the Department of Health; He acknowledges paternity of the child by an affidavit which he and the child's mother complete at the time of the child's birth and which is filed with the state registrar of vital statistics; He and the child's natural mother are or have been married to each other and the child is born during the marriage or within 300 days after the marriage is terminated by death, annulment, declaration of invalidity, divorce or dissolution, or after a decree of separation is entered by the court. See: Living in the Home of a Relative or Legal Guardian