Hello Annette,
Some thoughts.
1. Re a possible death of Isobel (WEBSTER) KETTLES.
I see from the IGI that Thomas KETTLES & Isobel WEBSTER married (1783) in Errol, Perthshire, had children - Thomas, John, Matthew, Janet - christened between 1784 and 1789 in Errol, and then had a child - Jean - born 1791 in Longforgan.
A check of the Family History Library catalog on the FamilySearch site at:
http://www.familysearch.org/indicates that the Longforgan church records do not include burials for the relevant period.
Booklets of pre-1855 MIs (Monumental/Memorial Inscriptions) for Perthshire have been published. If you belong to a local genealogical society, you might be able to consult them there as they would very likely hold the booklets. Otherwise you could post a specific query for an MI lookup on RootsChat.
2. Thomas KETTLE(S) and Margaret HARLEY.
Re the 1808 marriage of a Thomas KETTLES and a Margaret HARLEY - do you have a source for that? I can't find
any marriage between a Thomas KETTLE(S) & a Margaret HARLEY in the IGI - International Genealogical Index - on FamilySearch, or in a free search on ScotlandsPeople).
I see that a Thomas KETTLE & a Margaret HARLEY are recorded in the IGI as parents of the following two children - Charlotte Mathew KETTLE b 1818 and Charles KETTLE b 1820, both in Dunbarney, Perthshire. Also in Dunbarney with father Thomas KETTLE but no mother named are the following KETTLE births which may or may not be relevant (but note the middle names) - William b 1793, Catherine Mathew b 1796,
Hellen b 1808, Robert Matthew b 1810, James b 1815. (The relevant Dunbarney batches in the IGI are C113475 and C113476.)
3. Any connexion between the two Thomas KETTLE(S)s?
Do you have any reason to connect the Thomas KETTLE who had children with Margaret HARLEY in Dunbarney, and the Thomas KETTLE(S) who married Isabel WEBSTER in Errol and had children with her in Errol and then one in Longforgan?
Have you downloaded from the (pay-per-view) site ScotlandsPeople at:
http://www.scotlandspeople.gov.ukany of the OPR entries for the 1783 marriage and/or any of the births/baptisms to see if there are any clues?
Best regards,
JAP