Thanks again Jim for that further clarification
Reading your discussion with Frances setting out some of the issues about the numbering/indexing etc problems with films & will transcrpition has been very helpful to this novice. Being in Australia I used LDS film but hopefully on the trip to IOM this year I can use what sounds like more accurate records in the Manx Museum.

With regard to confusing dates on wills, when I was looking to confirm the death dates for both Margaret Camaish's, as well as the will I also looked at the burial dates on the IoMFHS Lawson Micro Site & compared what Donna & a fellow researcher here sent me from the Bride Burial Register. That way from different sources I thought I might get a more accurate date. Bride Parish & IoMFHS site burial index both have the mother buried 9 January 1772, with her daughter Margaret nearly 2 years earlier; buried 20 March 1770. So from the above, your comment about the will for Margaret Camaish alias Christian being 1772 is right.
Regards & thanks
Shan