Sophie Mack is his great-grand mother, but not sure which side (Leonard or Fanny). One source says mother, another says mother-in-law.
* https://familysearch.org/ark:/61903/1:1:X7DZ-5Y2
* https://familysearch.org/ark:/61903/1:1:K3TL-6H3
Which also makes me wonder which side Yetta falls on. She's described as Sister.