If you examine the census of 1850 for Blackbrook,Ny. You will find on page 153 a listing for Francois Plankey Age 46 and wife Sally (Salomee)Age 32. The listing also gives the names of 9 children that were still living with them in 1850. Eycria -Age 23,Laosque - 19, Betsey -17, Lewis -14, Ka-blin -16, Mary -11, two others one male and one female 6&4.and Esther -3. I believe these are the 43th Great Grandparents you are searching for. In the 1870 census only Sally age 49 and a daughter Sally Age 13 are still living in Blackbrook in one house. Francois must have died by them,and most of the other children must have moved out or married.