I wonder if someone who is a bit more experienced than me could give their opinion on the following please? I'm fairly confident about it, but it never hurts to check.

I've found in the OPRs for my family, the Mor(r)isons a reference to a place called Bognie near Forgue in Aberdeenshire. So using that as my point of reference, I've managed to find Mor(r)isons back to 1689 in the OPR. I also ran a search on the NAS website, and found a few nuggets. There was an Alexander Morison granted lands at Bognie in 1635, then from about 1660 all the mentions are of a George Morison who married the Viscountess of Frendraught. My ancestor is a James Morison, born 1689, the son of Alexander.
So, what I'm thinking is that Alexander who had the lands granted in 1635 had two sons - George and Alexander. George was the eldest and inherited the majority of the lands, and Alexander got a smaller portion which became known as Brae of Bognie?
I'm just concerned that it's a big leap of faith really - especially since the furthest I've got back with any of my other lines is about 1750! Plus my line ended up in Manchester, so I've no idea about Scottish property laws or anything like that....
All thoughts appreciated!