Hello Frances.
All the information you found is very interesting. Hopefully those Liverpool Corkill descendants will come back to the board - they should be very appreciative of the amount of detail you have discovered.

Just a couple of things I didn't follow (not unusual). You wrote first doc (SSS Oct 1778 58) "marriage contract for John - dated 18 May 1770;Thomas Corkill + wife Isable obo son Thomas" - did you mean marriage contract for Thomas, not John?

Also where you have "Wm Corkill + wife Hannah - the parents of my late wife..." should that also have been Thomas?

There was a father James Christian having children in Bride around the right time, but no Ann or Hannah that I saw.

Sue