Hi Harvo,
Oh dear. 'very plausible' isn't exactly a gold star.

Yes, John's an unknown quantity, and with a name like that,
we may never learn much about him.
None of the three THOMAS's appear to have left a will, so no
help there. I can't find a reasonable burial date for Hannah
at least within the Forest.
I wondered if Hannah had any support from the parish, but there
is nothing to be found for her as MALSON. There is an Overseers
record for a Hannah THOMAS, Abenhall but sadly not until 1825.
(Gloucester Archives Genealogical Database ref P220 OV 3/2/77).
My main stumbling block in getting to grips with your problem
is that I am not clear why the baptism of Nancy is an issue.
At the moment, I am unsure as to how I can now help, but once
you and David have had the opportunity to confer, and either
find flaws in my reasoning, or come up with other questions,
perhaps we will be able to progress, so do let me know your
thoughts, or any conclusions you reach.
Regards, and to David also.

vv.