My great-grandfather's name was Raymond Joseph Acker and he was married once and had a son, then married a second time and had 4 children: Lawrence, Joseph, Clark, and MaryAnn (not Marion). Lawrence was born in 1922 and died in 1923, so that's probably why you wouldn't have heard of him. I hadn't heard of him until recently when we started going through old family papers.
It's not exactly the same information but it's too close to disregard.
Here's all we know.
My great-grandfather was born GEORGE BURLEY on 12/17/1898. Edward Acker and his wife Margaret Goodrich Acker adopted George Burley on November 15, 1907, and changed his name to RAYMOND JOSEPH ACKER. He was a month shy of 9 years old at the time of the adoption. According to my grandmother, Raymond had a twin brother. Each twin was adopted by different people due to the fact that their names appeared on the last of one page and first of the next. The Ackers didn't know that there was a twin until it was too late. They went back to try to adopt the other child, but that child had already been adopted. There was no confirmation in the papers that we have that Raymond had a twin brother, so that mystery will persist. Raymond Joseph Acker lived in Buffalo, New York. He was a musician and drank too much and died of tuberculosis on 12/21/1931.
His son Clark Anthony Acker was my grandfather. My grandfather died in 1980 and his entire family is gone--his mother, brothers, and sister. The information I have is from his wife (my grandmother).
Raymond Joseph Acker married Anna Christina Doll on 3/15/1922. She was born 12/22/1905 and died 10/29/1998.
Raymond and Anna had four children. Lawrence Acker born in 1922 sometime, died 3/7/1923 Joseph Raymond Acker born 1/25/1924, died 5/31/1999 Clark Anthony Acker born 9/12/1925, died 8/23/1980 Mary Ann Acker (Conklin) born 8/22/1928, died 4/18/1956
MaryAnn died at age 27 of multiple schlerosis. She had no children. Joe married and had 6 children. We are in touch with them. Clark married and had 7 children, my mother among them.
According to my grandmother, Raymond had been married before he married Anna and had a son with his first wife. We can't find any paperwork showing this first marriage. The son didn't live with Raymond and Anna.
Raymond Joseph Acker's son from his first marriage didn't live with his and Anna's family. My grandfather met his half-brother once, however. And it's quite possible that the first son would have been Raymond junior. Anna and Raymond didn't name any of their sons Raymond Jr and that could be why. Also, your grandfather was born in 1920. That fits. Raymond Joseph Acker was about 21 in early 1920 and old enough to have a son. He didn't remarry until 1922.
Please respond if this sounds at all close. I have a lot more family information if you are interested. I was astounded to find something that sounded so familiar on this website!