John

I think that my current landscape research will clear up some of the questions but it creates a lot more.

If we look at the Creer holdings in 1511/13,
1. Balladhoo Santon is absolutely a boundary holding
2, The Dhoon East Baldwin is the last inhabited house in the south of the Island - next stop Sulby Glen
3. Ardwhallan, West Baldwin has a similar "top of the valley" position to The Dhoon.
4. Port-e-Vullen Maughold - not obviously on a parish boundary - however no Creers there c1490.

5. The situation of Shochlague is interesting: the treen is on the parish boundary, but the 2 quarterlands are not. Could this be that the Creers were demoted treen lords, carrying on as tenants of parts of their former domains? Speculation.
6. At Whitehouse, Michael, we are not near a boundary as far as we can tell, however the Creers were not there in 1490 either - there was William McHelly, Margaret Ine Alexander and John MacGilVorry
7. No more McCreres but in Andreas we have 2 holdings belonging to McFrosts - the Gen. of frost would give Mac+Rioagh wch I suspected suggests they are of the same ilk;
Looking at Cubbon's map, one of the McFrost holdings is bang on the Bride boundary part of Ballacottier in the Treen of Balytyrm; paying 6s 8d rent. Transferring back to 1490 and they disappear, the two 6/8 holdings correspond to one 12s holding of the McRobyn family,
8. The other Andreas holding in Mollenlawne treen is already held by John McFrost in c1490.
It is at Ballacrebbin and could be near the parish boundary

So... still an open possibility that McCrere means son of someone residing near the end or boundary!! Way-out folk.