thanks for the thought. I do not have a copy of the Radcliffe HISTORY of KK Maughold and have been trying to get hold of a copy, but I did note down the relevant section in the MM.
Basically the Radcliffes tell the same story as J A Brew, viz
Edward Xtian 1583-c1625 then his son
Robert Xtian c1604-1668 then his son
Edward Xtian born ??? to 1692 then his son
Ewan Xtian 1644 - 1712
THEN Younger Brother
John Christian 1646
Brew's birth estimate for the second Edward of 1628 must be wrong as he would only be 16 when Ewan was born, so it cannot be after 1624 if Ewan's DoB is right, and that is a bit shaky.
Adjusting the dates to what is rational the tree fits, but whilst we have two sources Brew & Radcliffe saying the same, that is suggestive but not proof as one may have copied the other, and an error if repeated enough becomes "fact".
What I am hoping for is some hard evidence that one story is wrong. A W Moore also offers a family tree but it seems to contain even more probable errors.