Naming patterns perpetuate the memory of family members through the generations. Those used by our Andersons suggest an adherence to honouring parents and grandparents which makes Maria Menzies's name all the more puzzling. I have found nobody with those names anywhere in our family and very few in the records. Yet, the column of her birth record headed 'After' has her named for “M.M.”
One Maria Menzies I found was born in 1785 and married master gardener William Todd in Edinburgh in 1806. I am fantasising that this was Martha Bain/Anderson's natural mother for these reasons.
The first daughter born to a marriage was named for a grandmother. Neither of Maria Menzies A's grandmothers was Maria or had a family name of Menzies.
Maria Menzies/Todd's mother's name was Ellen. The convention was that the fifth daughter was named for her great-grandmother. The fifth daughter born to David and Martha was named Ellen Martha, a combination that fits with Ellen Menzies and perhaps Martha Brown/Bain's mother.
The other daughters with a second name honour Martha Bain/Anderson's perhaps adoptive mother, Martha Brown. That is, they carried a family name so that I am assuming so did Maria Menzies A.
From this slim rationale, I am wondering if Martha Bain/Anderson was the natural child of Maria Menzies, adopted by John Bain and Martha Brown. I have found no record of John and Martha ever having had a child. It wasn't until 1930 that adoptions were formalised in Scotland. Prior to that, the arrangements were kept within the family, less frequently organised through the church. As well, census records do not exist before 1841 although it is sometimes possible to find information through directories or similar. But not, frustratingly, for John Bain and Martha Brown.