Looking for Relatives

I'm trying to find relatives/siblings/nieces/nephews/cousins of my grandmother. My grandmother was put up for adoption in the early 1930's in San Diego, Ca. She was born Diana Ritchey in 8, Aug 1934, her birth parents were Warren Ritchey (17 Oct 1907) and Dixie Cox (1910). We have her original Birth Certificate that has that info on it, it also states that her bmom had 2 children at the time of my grandmothers birth. We're unsure if that 2 children included my grandmother or if my grandmother made child #3. My grandma was adopted by the Killy's around her 3rd birthday in 1937. Thank you.