They are in the 1880 census:
Jacob Weme Sfelder 47
Mary Weme Sfelder 48
Joeanna Weme Sfelder 19
Abram Weme Sfelder 15
William Weme Sfelder 11
Isaac Weme Sfelder 9
Mary Weme Sfelder 8
Mary Fairhedge 83 Mother-in-law
Home in 1880: Walworth, Wayne, New York
All of the children were born in New York
Jacob and Mary were both born in Holland.
One tree has Mary's last name as Triestram but no source information.
That same tree has a picture of the Wemes children as adults
Standing from left to right Sara, Frank, Ella, Hattie, and John. Seated are Mary and Jacob III.