I will try to assemble information about these interrelated old families in Raymond & Windham Maine.
Barbara Plummer (born 1923) was an 'adopted' daughter of Daniel Lamont Plummer (1864-1942) and Leona Proctor-Shaw-Plummer (1883-1965). Barbara was clearly much younger than her father (almost 60 year age difference), but was potentially the biological mother of Leona (but that would require Leona having a child with another man in 1923 while still married to Daniel.
For the 1910 Census, Daniel & Leona had been married about a year, and they had their first biological child, William in 1910. But living with them were three children: Milton, Fred, and Edna Shaw, at 9, 8, and 6 years of age, respectfully. These were likely her children from a prior marriage (to a Shaw?)
For the 1920 Census, Daniel & Leona had the following children living with them: Milton Shaw (19 years old, and matches the 1910 Census), Fred Plummer (at 18 years old, and has taken his stepfather's name), and young William (now 10 years old). Edna had moved out, and married Eldridge York.
For the 1930 Census, Daniel & Leona had the following children living with them: Fred Plummer (at 28 years old, again having taken the name of his stepfather), William (now 20 years old), Frank Plummer (9 years old - is this a bio child?), and Barbara Plummer (6 years old - we know she's adopted).
For the 1940 Census, Daniel & Leona had the following children living with them: Fred Plummer (now 38 years old), Frank Plummer (now 19 years old), and Barbara Plummer (now 16 years old).
Now, Leona's parents, according to various sources, were Fred Proctor and Rebecca Gerry.
So, who were the bio parents of Franklin & Barbara Plummer?
Franklin Plummer's birth record says that his parents were Daniel & Leona. Daniel would have been a 55 year old father, I guess that's possible.
Barbara Plummer does not have a birth record under that name. As stated above, if her birth parents were Daniel & Leona, Daniel would have been 60 years old at the time. It's been stated by the family that Barbara was definitely adopted. From other records, I've learned that she was born 10 Sep 1923. I cannot find a Maine Birth Record from that date that has the first name Barbara.
Barbara married Arnold Mayberry (1924-1994) of Windham. Arnold's parents were Leroy Mayberry and Marion E. SHAW (1901-1982). No relation to Leona's husband Charles G. Shaw.
Daniel Plummer, Barbara's adoptive father, was brother to William Herbert Plummer of Raymond. Barbara was a long time 'cousin' and friend to the family next to the Raymond farm, and ended up owning more of the Plummer land in the 70s. Barbara was known as the lady with the pet capuchin monkey that terrorized the family who came to visit.