Thanks to all for your efforts. The vast majority of Corjeages are in Michael.

The other main parishes where there are baptisms, marriages & burials are Ballaugh & Jurby where most present as Cavendish - in Ballaugh only 3 and in Jurby only 2 burials are Corjeage and there are no MIs. All those in Braddan, Douglas and Onchan are Cavendish. I know of only one marriage in the 18th century in each of Lezayre, Lonan and Rushen and have not come across any burials there. In Patrick there is 1 Corjeage marriage and in German I have found 1 marriage each for Cavendish & Corjeage and a couple each of baptisms. The IGI has a baptism in Bride which I haven't checked with the register.

I'm not aware of any Andreas wills, but that needs further research. In the census the only appearances in Andreas are: Cavendish, Male servant, 15 (1841), Cavendish, female servant, 19 born Bride (1851) and Corjage, female servant, 21 born Andreas (1861) - 'born Lezayre' in 1851. It's a possibility that this last one could have had an illegitimate birth but I haven't got access right now to the Andreas registers.
I wouldn't like to suggest that I think I've found every Corjeage ever, but this appearance in Andreas is a bit of a mystery...