Hi there! It's been a while. But I am still a-huntin. I did find a Mary Ann McGillis b. 1879 who is the sister of a Sarah McGillis both daughters of Alexander McGillis and Jennett Stewart. Alexander and Jennett were both born in Scotland. A possible connection. There were other siblings of Sarah and MaryAnn: Janet, Joseph, Catherine, Euphemia, and Stewart. They lived on Manitoulin Island in Canada. Let me know if there is any connection.