there ia a Jane Watterson buried in Rushen 18480527 age 33 (no other info in bur reg) who fits very well as dau of Edward Keggeen with her death a few months before Mark remarried to the Ann Harley (who came from what appears to be an interesting fam !)
The whole of Edward Keggeen(or Keggin) + Cath Gell family appear to be missing from 1841 Manx census but were all baptised in Rushen