I can't be sure they are the same people, but check the marriage of Donald McDONELL and Catherine GRANT, Catherine, b. 1807, was the dtr of [Donald] Alexander GRANT and Ann/ Nancy CAMERON of Williamstown. Alex's will, written in 1828, says his dtr Catherine married Donald McDONELL. The names and dates fit.
My husband descends from Catherine's brother, James, so I haven't done much research on Catherine's line.
Joy Weaver