A huge word of thanks to Brian and an example of how important wills have been in verifying and correcting infomation that I had gathered from other sources.

I had been unsuccessful in finding the parents of my ancestor, Richard Christian, christened in Rushen July 15, 1787. The IGI gives his parents as James Christian and Jane Costain. This agrees with the Parish records )I checked in person).
However, there is no trace of any marriage of James and Jane in the IGI. I found the marriages of John Christian to Jane Costain and of James Christian to Isabel Costain. Jane gave birth to Esther Christian in September 1787, so that ruled her out as a possible mother for Richard.
Isabel however, per the IGI, had sons (John, Thomas and James) and daughters (Ann and Margaret)none of whom was born between 1786 and 1788. Now, thanks to Brian's index of wills, I was able to examine Isabel Christian's will (1830),and ascertain that she left legacies to four sons (the above three plus Richard!) and one daughter Ann Corlet(née Christian) and to two grand-daughters (Elizabeth Corlet, the daughter of Ann, and Margaret Crebbin, the daughter of the late Margaret Crebbin, née Christian). I do not know what was going on at Richard's Christening to cofuse Jane and Isabel.
Inspired by this, I located the will of Isabel's mother Ann Costain (1782). I am now eagerly waiting to see the wills of Richard and of James (Isabel's husband).
While looking for these wills, I wondered if it would be possible to electronically reprocess the films enabling each film to be limited to one or two parishes.