Hi Sue,
I agree it's not looking good for John & Phillip being brothers which of course brings the whole "house of cards" tumbling down!
There may be one last hope - Lonan SSS Oct 1736/32: Phill Hogg to John Hogg and Lonan SSS May 1746 Jo Hogg & uxr to Phil Hogg.
Their relationship if any may be mentioned in one of these, especially the latter [may even name the "uxr"], and the lands named could correlate with Lonan Property records. I will look them up next time I'm over but that may be some time yet.
In the meantime, I will digest all this latest data you have collected, looking for alternatives!
Rgds
JohnL