Here is a hint to work on confirming. If you search the 1892 census for New York State at www.familysearch.org
, you will notice Martha Sidney is listed twice, once with a birthdate of 1817, and once with 1818. If you look at the image for the 1818 one, you will find a Williams family listed above them. The father is Henry A. Williams, no Mother listed. However, there are children named George N. Williams, and another named Martha. Then if you search this same family in 1880, the Mother's name is Ella, age 28. The 1870 census shows Ella, age 18 with Martha Sidney. I will let you know what else I find.