I always like meeting someone who enjoys family history, so I don't see you as prattling on, but as someone I can explore family with and probably learn from since we may be connected, also you live "closer to the spot" and know the geography better than I. Peter Gemmell was the previous farmer at High Todhill, but I don't know if he was related to Andrew Gemmill, Christina's father. He was married to Janet Dunlop (nee Orr), a widow, who was older than he and already had children. They had no children between them. I have written down somewhere that Peter is a brother of Alexander Gemmell of East Tannacrief Farm, who married a Janet YOUNG. All these Fenwick families are so interconnected!
I don't know anything about Christina Young's siblings, but maybe I will try to follow up and see if I can learn something about them. The youngest son, John, age 29, seems to have taken over at High Gainford after Andrew died. He had two older brothers, James and Andrew, but they appear to have left home. There are also a number of sisters as they were a family of 9 children.
The Margaret Hopkin Gemmill (or Gemmell), who is related to me, was actually married to John CURDIE, and it was her daughter Elizabeth who married Robert Lambie and had two daughters in Penninghame, Wigton (Newton Stewart), Margaret who m Peter Bryson, and Agnes who m Thomas Edgar. I know nothing further about either one. Margaret Hopkin Gemmell d 1912 in Newton Stewart.
Please check with your friend about William John Gemmill and we'll see if he fits in anywhere.
Good luck, Hugh