I'm more sure now that the painter Thomas born 1812 s/o Thomas Gelling and Ann Moore is the father of the illegitimate Ann Catherine b 1834. I've looked at all the Thomas Gellings who could possibly be the father and he's the only painter. His youngest children born in IOM after his 1846 marriage had painter or house painter as father's occupation, as did a daughter's marriage.
The Mr Joseph Gelling who was buried in Braddan age 24, and who I think is the 20yo draper with Thomas in 1841 in Liverpool is still a mystery. He is not Thomas's brother because Thomas's father Thomas had an 1835 will that listed all children by his "present wife namely Ann Gelling, Thomas Gelling & Daniel Gelling" doesn't include a Joseph. :I no longer think he can be a son of Thomas's uncle Rev'd Alexander Gelling of Arbory because the Arbory records for the time period are clear, don't show any gaps and surely the Vicar wouldn't forget to baptize one of his own. I'm out of clues now, other than the "Mr" in the front of his name to indicate some importance.
Denise, you are right, Thomas the painter isn't one of yours, nor is he one of mine either.