XTIAN = Christian - a very common Manx name - you will find thousands of them!

bp Maughold and non-Manx names generally indicates residence in Ramsey - that ties in with my suggested 'smuggling' connection as Ramsey was a main port

Graham is not a Manx name but scotish - Ramsey was strongly linked with Galloway as two ends of the smuggling business

Bp in Braddan almost certainly indicates a Douglas residence - by mid 1700's Douglas was the main port and centre of all commercial activity

why not try to see how many families there were ? - then consult the burial registers to see if any buried on the Island - if not then you have a merchant family with strong links elsewhere with just the younger sons etc on the Island

you may like to continue this privately with me