What is this business with Vanessa being a Step-Grandmother?? She is no relation AFAIK (frankly I don't see the point of taking an I-patch to that degree even if it were true, she has no bearing on your blood or your upbringing so it wouldn't be incest).
If she were George's (Grandfather) Sister that would make her your Great-Aunt (or Step-Greataunt I suppose if you have decided George is a Step Grandfather)... Your Step Grandmother would be the mother of a Step parent... Your Great-Aunt's Daughter would be your first cousin once removed