I have known about my older, illegitimate half-sister, Dorothy Ann(a) Patterson/Hatch since about 1973/4. Little information given out due to birth circumstances. All I was told was that she was named for deceased paternal aunt Dorothy Anna; mother was named RUTH PATTERSON and said-to-be family friend of Pop's family(HATCH); born in the Seattle/Tacoma/Olympia area sometime between 1950 and 1956...after other half-sister, Toni (same dad) and before Pop met my Mom.
All reliable sources now deceased. ALL I need are the birth/death dates of sis and her mother, please. IF still living, all further contact is left up to my sister as I do NOT wish to cause issues. ALL I want is the basic minimum information my family history records.
ANYONE with even a shred of information is asked to please help! I was unable to get this information before 2 of my 3 other sisters died from cancer.

All SSDI searches have not shown anyone in correct time frame for birth dates and IF ever married, those last names were never revealed to me.

(P.S. Shortly before his death, Pop was just barely able to confirm to me that I did have another older sister named for our Aunt. He tried to tell me more, but couldn't.)