I think one of the marriage entries you're referring to is:
"John Bridson (Giles) & Marg Bell (Nanck) April 15 [1750]".
Later on the same page, same year is:
"William Bridson (Silv'r=Burn) & Elizabeth Bridson (Giles) Nov'r 11'th"

I looked through the list of Place Names for Malew in the Manx Notebook to see if I could find any reference to "Giles" but without success. The explanation for Ballagilley says that this was known as "Gill's farm". Perhaps "Giles" is a form of "Gill's"?
"Bell Nank's Land" is listed with the explanation that in 1703 Man. Roll it was "Bell of (Balla-)nank's land". This probably links to Marg Bell (Nanck) in the first marriage.

I have a mystery name from the Malew register as well.
Baptism: "Wm Son of Wm Gelling (vary) & Elinor Bridson his wife Dec'r 12th"
Burial: "William, son of Wm Gelling vary Dec'r 17th".
What is "vary"? It's been transcribed as "bary" but it looks more like a "v" than a "b".

Perhaps Frances will be able to help with these?