This guy, Virgil Sands, married a woman named Edith Marie Plimmer on August 23, 1930
They had 3 daughters - Maralee in 1931, Dorothy Ann in 1934, and Elizabeth Ellen in 1933. Known as Betty.
Virgil and Edith divorced.
This is Betty at around 15
This is Dorothy,
about the same age
This is Maralee at 29
Here are the daughters of the three sisters.
Betty's daughters are Wendy, born in 1956.
And Kathryn born in 1961.
One of whom is likely your grandmother.
Kathryn had twin boys in 1957. She gave them away.
One of them could be your mother's father. Though the age might not work out.