I hope that this message reaches you and finds you well. I have been doing some more research into the family line and have at last found a definite link between your John Francis and our George Avern. John Francis is one of the witnesses on George's marriage certificate and George also was in St. Clement, Dundee on the 1871 census. The only way to confirm they were brothers would be who John Francis' parents were which would be on his marriage certificate to Helen Laverock, do you have that? Or know who his parents were? George's parents were John Avern and Charlotte Wright, but I believe he may have remarried later on to an Emma Matilda Avern (this bit I cannot fully confirm as yet). It would be lovely to hear from you, if you can contact me directly on my email address I will give you my telephone number so we can have a chat.