I spent a bit of time reviewing everything written on this thread (and there's been lots!). I think the QUINE/KISSACK side of your tree makes sense but the GELLING side doesn't.

On Oct 1 (at 1:01PM) I posted a conclusion that your William GELLING (who married Margaret QUINE 1816) could not be the one bp 21 Jun 1795 son of John GELLING and Elizabeth OATES (of Ballamillaghyn, Braddan), because this William died in 1820 age 25. So, this is the wrong family for you. However, it would be worthwhile to check the three John Gelling wills ca 1854-5 one of which is likely to be the father of this William, or the will of Elizabeth 1855. If I'm right, there won't be a mention of son William because he's long dead.

Who is the right family is a whole different matter. Of the 3 William GELLINGs on the IGI born about 1795, we've eliminated the OATES one so it leaves John GELLING & Isabel CAVENDISH of Braddan or Robert GELLING & Jane KELLY of Marown. It also may be a different couple, not on the IGI. At the moment, I'm stumped on the parentage of William.