if you are fairly confident of 1787 then possibly john s/o william baptised Lonan 1787-03-11 - however if you look at manxnotebook for Lonan you will find that marriage regs are incomplete - it is possible that the parents were William Callow + Margt Kelly but there is a gap between children - you will probably need to check out many wills - some are summarised on Manxnotebook other may be in full on www.lawsons.ca but welcome to the joys of researching Lonan!