Lannanta - I decided to try and tidy this little lot up a bit before wandering back to my Trewhella families.
Working from the 1841 Census we find siblings John, Thomas, Ann and Mary all living together at Noonvares.
There is no sign of Thomas or Jane so it would appear that both parents were deceased prior to the Census.
Also missing are Abel, William and Elizabeth although we do know that Abel Glasson married Sophia James at Breage in 1838.
You have already mentioned a burial for Jane which I believe is certainly Jane Goldsworthy.
Jane Glasson age 41 buried 30th March 1833 Crowan
William Glasson age 16 buried 23rd June 1837 Crowan (I believe this will be our 'missing' William from the 1841 Census)
Thomas Glasson age 50 buried 18th May 1839 Crowan
No doubt that this will be the patriarch of the family in question which now gives us a possible year of birth of about 1788/9.
Based on that the 'best match' would be Thomas son of Canady (Kennedy) Glasson (sometimes Gleeson) who was baptised at Falmouth in 1789.
I don't know who this Canady/Kennedy was but the only references to him I can find are a couple of baptisms at Falmouth!
The only other Thomas Glassons who would actually be a closer match were the two sons of Robert and Eleanor at Cubert or the son of William and Thomasin at Ludgvan.
First Thomas s/o Robert was buried in 1790 and the second given the name Thomas Love Glasson and buried in 1792.
Thomas son of William and Thomasin was buried in 1790 which means there is literally only one known candidate left!
Born 11th March and baptised 12th June 1791 at Crowan son of John and Margaret.
Given that the identity of Thomas is the correct conclusion (hoping there are none lurking in fine print between the lines of the PRs!
) then I think your hypothesis is very likely correct.
When John Glassant married Margaret Richards he signed as 'John Glasson junr' and one of the witnesses was Edward Glasson who I suspect was his brother and also the man who married Rebecca Harvey and then Elizabeth Trevena.
The one other item I think you queried was the 1835 marriage at Crowan between Thomas Glasson and Elizabeth Webb.
There is no record of Thomas having been widowed and no record of his occupation in the marriage register.
He signed with his mark but unfortunately I do not have a copy of the marriage of Thomas Glasson and Jane Goldsworthy for comparison.
The witnesses were William Richards and John Goldsworthy.
That should help a little.
CT