As a result of your suggestion, I contacted the Victor Genealogical Society (http://www.victorny.org/Data/Documents/Town/History/Spring20...), which I found when I Googled Ontario County History. They are working on a response but it's been a while and I assume their staff and resources are small.

Though the 1880 census is the starting point for my research of this family group, I am having a particularly hard time pinning down Amos and Sarah. His surname is given as Eldridge while the family info I have suggests it was Eldred. There appears also to be another Amos Eldridge I keep tripping over, apparently from the vicinity (Steuben Co.), who was born around the same time. I'd appreciate hearing from anyone who's had experience with this kind of roadblock.