Hi, David. I can tell you the parents of Benjamin Dow and wife if you are interested,
Isaac Dow and Rebecca Bessey were married 4 Jun 1809 in Kennebec Maine (dates correct, place may be wrong) they came to Atehns County, OH and had these known children and probably a few more that I haven't connected. John, Thomas, Warren, Benjamin F, Solomon, Isaac W and Lorenzo.
As you stated Benjamin married Syrena whom has been identified as Syrena Finch Bryam in some records. His brother Warren married Lydia D Bryam. Both these daughters I believe belong to John Wm Bryam born between 1760 and 1770 who died ca 1844 in Homer twp, Athens county, OH. John Wm Bryam was my 4th great grandfather. Will gladly share what I know.
I don't think Lydia and Syrena were sisters, but maybe related. Lydia and her siblings and their spouses are named in 2 lawsuits trying to settle their father's estate while there is no mention of Syrena.