It might be worth while to follow descendants of a Capt William Allison, Wilkes County down and see if there is an intersection. Capt William is an ancestor of mine through his son Thomas, and his granddaughter Elizabeth "Betsy" Allison who married Hiram Pipes. William was born in Cecil County, Md. and moved to Wilkes County. Fought in Rev War. Died 2/1818. Allow I don't see a listing for a Harrison, perhaps one of his children named a son Harrison. The use of the William name might be significant. Happy hunting!