Well, I see that Patrick Blyth (the younger) and Mgt. Watson had a son called John in 1750, and he could certainly have been the John Blyth who married Mgt. Reekie in 1780. But there were other families called Blyth in Abbotshall at the same time. If you know the names of all the children of John Blyth and Mgt. Reekie you might get a clue as to the grandparents' names.
By the way, I believe the Margaret Watson who married Patrick Blyth in 1744 is the Mgt. born at Dysart in 1714 to John Watson and Margaret Lindsay, who were married at Dysart in 1708. They had an earlier daughter called Margaret in 1708, but she must have died.
If you want me to really go out on a limb, I would suggest that this John Watson is the John born at Dysart in 1683 to James Watson and Janet Miln (m.1669, Dysart), and that his wife Margaret Lindsay is the Margaret born at Dysart (surprise, surprise!) in 1683 to Robert Lyndsay and Margaret Craigie (m. 1676, Dysart).
There you go, I've constructed a fine old Dysart pedigree for you, even if it is a bit of a castle in the air!
As for the Abbotshall lot, Patrick Blyth junior's parents Patrick Blyth and Isobel Inglis (m.1709) had a son called Andrew in 1710, so it's not impossible that Isobel may have been the Isobel born at Abbotshall in 1686 to Andrew Inglis and Janet Williamson (the Williamsons were a Dysart family!).
Incidentally, a David Blyth and Jean Williamson were married at Abbotshall in 1669 and had a son called David at Dysart in 1673, so there's a possible link between Blyth, Inglis and Williamson.
The OPRs of Abbotshall and Dysart are so well-kept compared to some (e.g. Borders OPRs) that it's very tempting to build up these speculative family-trees from all the information available. Well, you have to start somewhere! And if you get evidence that one of your "ancestors" wasn't your ancestor after all, you can always kill them off.
One last intriguing thought to finish with. I've mentioned the Williamsons of Dysart, and I know of at least one Robert Williamson who was fathering children there in the 1600s. Scotland's great 15th century warship, the Great Michael, is supposed to have been crewed by Fife men among others, and the only one whose name has survived as far as I know is a Robert Williamson, who was "a wright, of Dysart". He was probably the ship's carpenter, an important member of the crew.
Harry