Who was the Rev James Dunlop married to?

I have been going through an old photo album of my great aunt's, scanning the photos, as well as trying to work out who they all are. Apart from having many many photos of my ancestors in the Paterson and Macindoe families, it has produced some puzzles for me to solve as well.

The latest puzzle I've been working on is "Rev Dunlop" and his wife "Mrs Dunlop". According to the photos, the Rev Dunlop was married to one of my great great grandfather Thomas Macindoe's sisters. As far as I know Thomas had four sisters: Mary McIndoe (it seems that Thomas used the "Macindoe" spelling of his surname, but the rest of his family generally used "McIndoe"), born 7 April 1826, Margaret McIndoe, born about 1838, Jane McIndoe, born about 1840, and Jeanie McIndoe, born about 1843.

Of these four sisters I know that the youngest sister Jeanie McIndoe married Thomas Weir, from a marriage notice in the Glasgow Herald:

"At Albion Cottage, Helensburgh, on the 12th inst., by the Rev. James Dunlop, Motherwell, assisted by the Rev. John Lindsay, Helensburgh, Mr THOMAS WEIR, writer, Glasgow, to JEANIE, youngest daughter of the late WALTER MACINDOE, Esq., of Ashfield." Glasgow Herald, 13 August 1875.

I don't think it is too presumptuous to assume that the Rev James Dunlop who married Thomas Weir to Jeanie McIndoe was the Rev Dunlop who was married to Jeanie's sister, especially considering he was "imported" in from a different parish to celebrate the marriage. So, clearly, his first name was James.

Searching historical newspapers, I hoped to find a marriage notice for Rev James Dunlop. No such luck. However, I did find his death notice:

"MOTHERWELL. - DEATH of a U.P. MINISTER. - Yesterday morning the Rev. James Dunlop, U.P. minister at Motherwell, died in the 60th year of his age and the 36th of his ministry. Mr Dunlop, through failing health, found it necessary lately to resign his charge. He was born in Irvine in 1823, and was educated at Glasgow University, where he took the degreee of M.A. He laboured at Biggar for nineteen years prior to being called to Motherwell." Glasgow Herald, 26 January 1883. [U.P. stands for United Presbyterian.]

Googling him, I found out he had two ordained brothers, the Rev Hugh Dunlop and the Rev William Dunlop, and he himself was ordained on 14 April 1847, and he accepted a call to the Motherwell parish in 1866. Still no mention of a wife though.

I am guessing that the wife could be Mary McIndoe, mainly because she's the closest in age to James Dunlop. A search on FamilySearch revealed two options: two marriages between a James Dunlop and a Mary McIndoe - one a marriage in Biggar, Lanarkshire in July 1851, the other a marriage in Kilmaronock, Dunbartonshire on 4 July 1851. My hunch is that this is the same event, registered in two places, probably each person's home parish. I could check on Scotlands People, but I would have to pay then, and I prefer to do my genealogical research for free if possible. It must be my Scottish heritage!

Further searching on FamilySearch revealed children of the marriage, the first being named Walter Macindoe Dunlop. I think that clinches it - the first son named after Mary's father. Finally, I've worked out that the Rev James Dunlop was married to Mary McIndoe!