The family tree I have says that John Molison was the grandson of Francis Molison and the only child of John Molison and Catherine Spence.
That's possible too. I wasn't sure that I trusted that note!
Out of curiosity, I took a look at the baptism of the child born to John M and Fergusia Todd in 1770. The name is quite clearly Francis or Frances, not Fergusia, but there is no indication whether it was a son or a daughter. See attached.
Their fiirst son was John, baptised 15 September 1758 in Brechin. So they must have been married about 1757. So John, husband of Fergusia Todd, must have been born around 1730/1740.
Francis Mollison and Janet Skinner had 5 recorded children between 1695 and 1707:
Francis, baptised 28 March 1695
John, baptised11 August 1698
Janet, 4 August 1700
Margaret, baptised 16 October 1702
James, baptised 8 May 1707
So it is perfectly possible that John b 1698 was the father of John b about 1730/1740. In that case, however, it must be Francis b 1695, or even a younger Francis Mollison, who was Commissary Court Clerk in 1758, as their father (husband of Janet Skinner), would, if still living, have been too old to be doing such a job in 1758.
If John b 1730/1740 was an only child, who were the parents of Bailie David Mollison, who was John's contemporary and witness to the baptism of John's child Franc*s in 1770?
However, there is a gravestone in the Cathedral Kirkyard which (according to the MI booklet) reads
1777. Francis Molison mert 28.7.1769, w Kath Spence 9.9.1764, David who survived his wife a few years only, by s John mert 19.5.1789 (w Fergusia Todd, survived by one s and one da); John Molison late provost Brechin 21.6.1791. So barring transcription errors, the stone seems to say that Katherine Spence was the wife of Francis, not John, Molison. All very confusing. (Also, shockingly sad, in that only two of Fergusia's 15 children survived her. Thomas was one; the other was Mary, who married George Whitson and died in 1856.)
Has anyone got a copy of the testament of Francis Molison, late Bailie of Brechin, who died 9 February 1722? It's a Testament Dative, so probably won't be very informative, but it might name his wife.