May I go back to square one and ask what is probably a dumb question? but I haven't been able to find the answer on reading the thread.
(Also a tip for reading a long thread like this: click "Print" up at the top and the entire thread will be visible which is so much easier for searching for info.)
Did anybody ever figure out who Amelia Carnarton was?
I also couldn't see whether the death cert for the Amelia Carnarton who died in 1842 was got.
Much more info is now available; her burial is here
http://www.cornwall-opc-database.org/search-database/more-info/?t=burials&id=1493285and she was 15 years old at death (residence Charles Street, Kenwyn), so she was not the Amelia aged 24 in 1841.
So is the 1842 death of 15-yr-old Amelia likely the Amelia baptised in 1824, with some age rounding? (or possible misreading of the microfiche if it said 18 maybe)
If no record of your Amelia's birth (baptism) was ever found, I also wondered about Amelia Bryant baptised October 1816 in Kenwyn, mother Mary Ann, no father named:
http://www.cornwall-opc-database.org/search-database/more-info/?t=baptisms&id=3223810There is no obvious marriage or burial/death for her in Cornwall, or evidence of her by that name in censuses. (An unmarried Amelia Bryant from Cornwall in censuses in Gloucestershire with father James in 1841, who died in 1893, is not her.)
She could well have been a daughter of Charles Carnarton before his marriage to Mary Duff.
(I don't see any Mary Bryant marriage that would offer a Carnarton stepfather.)
The Charles who married Mary Duff was baptised 1800 in Helston.
A Mary Bryant was buried 1817 aged 16 in Falmouth ...