Thanks for that Frances. Yes, you're right, it is Cavendish.

Isabel Kneal had an illegitimate daughter, Jane, ‘by John Darcy An Irish Man’ baptised in Lezayre 11th March 1756 Lezayre. Isabel seems to have married John Corlett, weaver in 1758, and in 1773 her daughter Jane Darcy married Richard Corjeage from Kirk Michael in Lezayre (‘with the consent of her parents’).

Jane and Richard had seven children in Kirk Michael, including Jane Corjeage (1781), who I believe to be the Jane Cavendish in Isabel (Kneale) Corlett’s 1799 will. Most of their children seemed to go by the name of Cavendish in adulthood.