I can't find a relationship between Margaret MacNeil's family and your family using SR MacNeil's book, ie no common ancestor because he does not take Margaret's family back beyond her father John D MacNeil and her maternal grandfather James "Lieutenant" MacNeil. He names John D.'s father Donald and grandfather Norman, but I don't see them in the book and there is no Piper's Cove section. SR says John D was from Pipers Cover which is near Grand Narrows, on the other side of the channel. John D is in the 1901 and 1911 census for Washabuck District both of which show him born in 1863 in Nova Scotia. His wife Mary Ann was also born in NS about 1860. There are so many MacNeils in that area it will take extensive digging on your part to find a relationship. Grassy Cove and Iona where your family is from are not far apart so I would expect the families knew each other. Since so many of the MacNeil families came from Barra there is a fair chance of a common ancestor there. More digging needed. Good luck.