Thank you for all the searching you’ve done to help.
It does seem she’s signed the certificates herself (both husbands say mark of whereas she doesn’t).
I think Roberts is correct in the most part because of the child’s birth certificate, I’ve ordered a birth certificate for the first union child to see what maiden name is listed on that.
Like you say it’s a knotty problem and might only be solved with a few hours trawling through baptism records. My relative who’s been working on this too is wondering if Emma was a middle name - wouldn’t be unheard of people changing their names by the time they marry
Morris really is a common name and typically that’s the name of the other side of my maternal tree!