Actually a number of the IGI entries are 'Patron' entries and are not confirmed by an entry in a Parish Register - my guess is that there are no more than 15 or 20 at most people over a period from 1700-1760 - some entries appear to be duplicates (ie same name, same date 2 different parishes) - my opinion is that anything not backed up by a parish entry should be treated with a great deal of caution if not actual disbelief unless you have other evidence (eg from Wills, burial registers, Memorial Inscriptions (though your dates are too early to hope for many of these)

I suspect you have 4 families at most - a surprising number of illegitimate children in which father named in register - also looking at the marriages many are to non-manx names - sounds to me very much a come-over family with some children marrying on the Island and then emigrating though a couple of the men married Manx girls but judging from lack of records moved off the Island

I didnt find your Margaret McHood=Phillip Christian in the on-line IGI but there is a patron entered marriage (ie a guess ?) in Ballaugh