John McAdam married Jane Ferguson on 10th Oct 1864 at Lisburn Register Office. Both lived in Ballykeel, parish of Dromore, Co. Down.
https://www.irishgenealogy.ie/files/civil/marriage_returns/marriages_1864/11625/8279940.pdf
Griffiths Valuation (1863) lists Samuel McAdam on plot 25 in Ballykeel, which was just under 5 acres. That’s on the modern Ballynahinch Rd. Looking at the property today it looks as though there’s a modern house there replacing the 1860s buildings. The Valuation Revision Records on the PRONI website show Samuel McAdam deleted as tenant by 1872. He appears to have moved to a house and garden on plot 56a. Here's his death in 1892. Informant was son Henry who replaced him as tenant of that plot.
https://www.irishgenealogy.ie/files/civil/deaths_returns/deaths_1892/06039/4720261.pdf
There was a James McAdam on plots 23 & 24, so perhaps a relation? Samuel appears to have taken his property over until being deleted in 1872. The new tenant was a Joseph Hamilton. VAL/12/B/20/2A (1866 - 1881) at PRONI.
Here’s the family in 1901:
https://www.irishgenealogy.ie/files/civil/deaths_returns/deaths_1892/06039/4720261.pdf
And in 1911:
https://www.census.nationalarchives.ie/pages/1911/Down/Ballykeel/Ballykeel/249323/
Note Mary McAdam, niece, was born in Scotland, so there was evidently some toing and froing.
Family was Presbyterian so if looking for church records, the family may have attended one of the nearby Presbyterian churches. Possibilities are 1st Dromore (records start 1832) Banbridge Rd (records start 1851) and Drumlough (records start 1855).
Henry died in 1942. His will should be in PRONI (in paper format). Yoy cna view it there free, or pay PRONI to copy it and send it to you.
Probate abstract:
McAdam Henry of Ballykeel Dromore county Down farmer died 15 February 1941 at Lisburn and Hillsborough District Hospital Lisburn county Antrim Probate Belfast 7 April to Owen Keenan merchant and Hugh Jess farmer. Effects £493 0s. 4d.
This lady also has a will in PRONI:
McAdam Martha Jane of Ballykeel Dromore county Down spinster died 7 June 1924 Probate Belfast 13 May to Samuel McAdam farm labourer and Samuel Crawford school teacher. Effects £3.
Family in 1901:
https://www.census.nationalarchives.ie/pages/1901/Down/Ballykeel/Ballykeel/1240157/
1911:
https://www.census.nationalarchives.ie/pages/1911/Down/Ballykeel/Ballykeel/249288/
You can tell from the supplementary returns that accompany the census that the property in 1911 had walls made of brick or stone, a roof made of slate, iron or concrete, 2 rooms, there were 2 windows at the front and it had a fowl house.
This household in the townland then too. No idea if they are related:
https://www.census.nationalarchives.ie/pages/1911/Down/Ballykeel/Ballykeel/249283/
Ann McAdam death 1921:
https://www.irishgenealogy.ie/files/civil/deaths_returns/deaths_1921/05099/4400895.pdf
I don’t see a Ferguson house in Ballykeel but there was a William Ferguson in Growell which is just a few hundred yards away, so possibly that’s where Jane originated.
https://www.askaboutireland.ie/griffith-valuation/index.xml?action=nameSearch