I am doubtful that this marriage is our John George.
The listing for John George Genewyr in the book by Janice Gartman Lee, "The Snow Rowand Passenger List" (Lexington Genealogical Exchange, vol. 5:2, 1986, pp. 52-55) includes the wife (unnamed), Child Catherine 15, Child Michael 14, Child Adam 8
The plat for his land in 1753 and memorial for his land in 1765 uses Genewyr in SC archives.
There are also listings in SC archives for John George Jenewyr, as neighbor on land on Second Creek.
Subsequent listings for the family as neighbors in this area uses spelling Alewyne, Aleywine, Elwine, etc.