JC asked me if I could help with the potential Scarff and Gelling connections, as I have spent considerable time on both of these names. I haven't totally followed all the thread but think I have the gist of it.
There was a suggestion that Elizabeth Sophia Gill, d/o William and Margaret Gill in 1827 might belong to Robert Gell and Margaret Scarffe who married 1813 Malew and had daughter Margaret 1814 (md Thos Quilliam 1835). It turns out that Margaret Scarffe was over 40 when she married, and would be well into her 50s by 1827. These folks can be found in 1841 and 1851 census's in Malew. You can therefore scratch them off the list.
The 1841 census grouping at Ballafletcher in Braddan that includes Sophia Gill age 15 F.S. and Margaret Caley age 10, that has the John Gelling shoemaker family listed first, is interesting.
1841 census at Balla Fletcher, Braddan HO107/1463/5 2 21 pg 5 (464355)
John GELLING 50 Shoemaker Y
Elinor GELLING 50 Y
Elinor GELLING 20 Dressmaker Y
Elinor GELLING 50 Washer Woman Y
>John BRIDSON 60 A.G Labrour Y
Elizabeth BRIDSON 60 Y
>Sophia GILL 15 F. S. Y
Margaret CALEY 10 Y
John Gelling I think will be the one bapt 6 Mar 1791 Santon, s/o the mysterious Michael Gelling and Margaret Clague.of Santon. He married Elinor Corrin 7 Nov 1812 Kirk Rushen and they had 6 children which includes Eleanor b 1819 who is in the census. John Gelling had an older sister Ann who was an unmarried washerwoman age 62 in 1851 in Douglas, and who is missing in 1841. I think the washerwoman Elinor Gelling 50 should have been "Ann" and the census taker carried the name "Elinor" one person too far. I don't know of any connection to Elizabeth Sophia Gill or to Margaret Caley. I also have no knowledge about the Bridson couple at Ballafletcher, beyond what is mentioned by David Dwyer in this thread 6/7/2013.
Like JC, I suspect that Elizabeth Sophia Gill and Margaret Caley are related. Now that Maureen has found out that Sophia was an illegitimate daughter of Margaret Gill, perhaps Margaret Caley is a product of the same mother? Why they are at Ballafletcher, I have no idea.