Hi Dod
I am sure that you are correct, this is the most likely answer, and that the local clergy stepped in here. I see that Wikipedia states "The Scottish Episcopal Church is a Christian church in Scotland, consisting of seven dioceses. Since the 17th century, it has had an identity distinct from the presbyterian Church of Scotland.
As a member church of the Anglican Communion since 1867, it recognises the primacy of the Archbishop of Canterbury, who does not, however, have any jurisdiction in Scotland". It also states "The Scottish Episcopal Church began as a distinct church in 1582, when the Church of Scotland rejected episcopal government (by bishops) and adopted a presbyterian government by elders as well as reformed theology. Scottish monarchs made repeated efforts to introduce bishops and (the) two ecclesiastical traditions competed."
So the James Skinners I mentioned would have been from the 'rival' Episcopal church, and probably not acceptable to the congregation (although, no bishops to worry about!).
At first sight, when he died in 1852, Rev. Thomas Skinner would not have been exposed to his son's future wife's clerical relatives because they were not married until 1872. However, a strong family myth claims that Thomas (junior), who was 24 years older than his wife, said that he would marry her when he saw her in her cradle (she was born in 1851 in Edinburgh)! This means that, despite his father's UP faith, the family knew the Skinner family socially despite their notable Episcopal background, even before Rev. Thomas died - probably not surprising as I would imagine the clerical world was pretty small.
Although Rev. James Skinner, the grandson of an Episcopal bishop, was unlikely to be drafted into a Presbyterian church, his nephew James Henry might have had other views. It is also possible that this was purely a short term emergency solution organised by his son Thomas, by now a well established solicitor in Aberdeen, and that such clerical differences would be less significant. Who knows?
I agree about Forfar, although Dunlane is much closer. Also, even it those days, I would imagine that clergy had to travel long distances to obtain a suitable 'living'?
Chris