Perhaps you have the following, if so you can ignore
MASKENS, Harry Edward Gratte, 22, bachelor, Marconi Operator, of 8 Yalding Road, Bermondsey, son of Harry Edward Gratte MASKENS, decd, a Sketch Artiste, married 22 Dec 1916 at the Registry Office, St Olave, to Lilian WARBY, 21, spinster, a Music Hall Artiste of 6 Catlin Street, Bermondsey, dau of William WARMBY a railway clerk.
I think I now understand......your grandmother is Doris Adeline EDWARDS who is a half sister to Harry Edward Gratte MASKENS.
Cando