As for right now, that link is on hold, and I am still taking a break from it all.
January 2016 Jesse McRae presented his book, A History of The African American McRaes of Georgia, to the Georgia Historical Society. There is a great deal in the book that explains the connection of Mose and Daneil McRae.
Apparantly Mose's mother Mary was the sister of Daniel McRae, also the sister of Mose's mother in law Susan. Yes it looks like Mose and Matilda were first cousins, because Mary and Susan were the daughters of another Matilda McRae, which is where Matilda McAllister McRae got her name.
Mose's parents was Mary and Nelson McRae, and the only known siblings are Mary, Ann, and Betsey. There is possibly a half sibling also named Nelson.