I've only recently started to look into the family tree - you seem to have done a lot of research.
as for Charlotte Lay, there seems to have been two born in the area at that time and I assumed that ours was the younger one, but obviously the Census proves me wrong!
There are two Frederick Mansells registered in Witney - one in 1882 and one in 1886. Do you know which one is ours?
I shall have to register with one of the Family History sites if I'm to make any real progress.
By the way, one of my uncles, whom I never met, supposedly went to live with an aunt when he returned from WWII. It could easily have been an aunt on his maternal side, but I thought I'd mention it in case he happened to have gone to your Grandma.
Regards
Margaret