Would anyone be willing to help locate the burial for me please of William Cavendish in 1810/1811, which I can't spot on Brian's index?

From the joint Will of William & Margaret Cavendish of the town of Douglas:

27th March 1810 - signed
17th June 1811 - wife Margaret, the survivor, sworn in as executrix.

William & Margaret (Crellin) were married in Kirk Michael (both of this parish) in 1785. Brian has Margaret's later burial in Braddan:

CAVENDISH, Margaret 64 Bra 11 Oct 1823 CRELLIN

It would be an added bonus if there was an MI for either of them! Can anyone help?