Have you tried searching the 1911 for the 7 children separately? For example, I searched for Elizabeth 1897 born Leeds and there may be a match in Leeds shows age as 14.
If there were any other female Griggs' in those 7 children, you could try looking on free bmd for a marriage record.
I did see an Elizabeth Hannah Griggs on freebmd birth registered q/e Dec 1896, Leeds vol 9b page 477, could be your Elizabeth especially as her mother's name was Hannah.
Good luck searching
Shirl