oooo - I've just found some more children!
Someone on
Ancestry has:
Sarah b1805
Thomas b & d 1808
Elizabeth b1817<<<<<<<I've only checked her so far and have claimed her
as well as Mary Ann, my ancestor.
I've also found a Martha Balls christening in Patrington, Yorkshire (place of birth of Edmund's wife) to Edmund & Rebecca in November 1802.
It would seem likely then, that they married in Yorkshire - I've never had to search anywhere else in the UK apart from East Anglia & Devon - Are Yorkshire PRs on line anywhere?