Hi GroovyKiwiChick, I looked up the Donaldsons records in Co Down. I came to the conclusion with many more records on line since the late Tiffany started the query, that perhaps the ArdkeenArdquin/Portaferry area Donaldsons are becoming confused with similar first names appearing in Tullylish parish some fifty miles away. I add square brackets to info gleaned in others original work
Could your gt gt gt grandfather be Samuel DONALDSON [b~1782]] Ardquin[?] of Ballywalter [BUT the nearest townland of that name is in Ballywalter parish three parishes further northwards on the Ards peninsula.] Ardquin ; authority [ie the Bailiff] in Ballywallon 1836; died 31 Jan 1855 aged 73; husband of Margaret; father of Robert; buried Ardquin graveyardV17 p 127 OSM; MIs (Source RD = the frozen website of ROS DAVIES Co Down Website see archive up to march 2017 which has a mini database of Donaldson
https://web.archive.org/web/20140707175935/http://freepages.genealogy.rootsweb.ancestry.com/~rosdavies/SURNAMES/D/Donaldsonwho also has
Mrs Eliza DONALDSON [b~1806] Ardkeen nee Coulter; died 29 Aug 1838 aged 32; mother of Eliza of Portaferry ; buried parish graveyard MIs
Hugh DONALDSON [b~1836] Ardkeen of Ardkeen; died 10 May 1911 aged 75; father of William; buried parish graveyard MIs
Hugh DONALDSON . Ardquin of Ballywallon; died 14 Jun 1896; buried parish graveyard MIs
notes RDs Co Down parish maps are not available on frozen site. See another, respect its source please
http://www.sinton-family-trees.uk/maps2/down-parishes.phpstaying on Ardkeen/Ardquin parishes these are close to Portaferry at the bottom of the Ards peninsula. Portaferry may well be an administrative district for area
GenesReunited see
https://www.GenesReunited.co.uk has many Donaldson in Ireland, a brief selection of interest for you
Samuel Donaldson 1849 N. Ireland ... No Anne
Samuel Donaldson 1793 Ireland ... No Andrew
Samuel Donaldson 1790 Ireland ... No Neil
Hugh Donaldson 1841 Ballyphillip, Co. Do... No Val
Hugh Donaldson 1840 Ballyphillip, Co. Do... No Dianne
John Donaldson 1846 Portaferry, Down, Ir... No Val
John Donaldson 1846 Portaferry, Down, Ir... No Val
John Donaldson 1846 Portaferry, Down, Ir... No Sandra
the use of Portaferry made me further search RD these are a short selection
I left out several in Balltphillip. The parish on the bottom tip of Ards Peninsula
DONALDSON Brothers Ballyphilip took over the forge in Church St, Portaferry in 1885 JUAHS 1977 p27
Andrew DONALDSON . Ballyphilip of Royal Irish Rifles; on War memorial for 1st World War in Portaferry Presbyterian Church
AnneDONALDSON . Portaferrymentioned in the diary of Hugh Joseph Dorrian of Portaferry 3 Sep 1881 as plying the piano
John DONALDSON . Ardkeen & Ballyphilip son of Andrew Donaldson; aged 21 married Mary Jane Watson 2 Oct 1855 in Ardkeen; father of Sarah b. 7 Apr 1869 (regd. Portaferry) CR
John DONALDSON . Ardquin of Ballywallon; died 29 Aug 1882 aged 70; buried Ardquin graveyard; bailiff on Echlin's estate; son of Ann MIs
John George DONALDSON . Ballyphilip
regd. Portaferry ; husband of Frances Swanzy; father of Letitia Frances b. 5 Apr 1868 & Marion Swanzy Donaldson b. 18 May 1870CR
John DONALDSON . Ballyphilip regd. Portaferry ; husband of Nancy Smith; father of Eliza b. 10 Dec 1869 CR
John DONALDSON . Ballyphilip sang at Portaferry dramatic evening 16 Jul 1910 JUAHS 2011 p31
Robert DONALDSON . Ardquin died 26 Feb 1869; buried parish graveyard MIs
Samuel DONALDSON . Ardquin of Ballywalter; authority in Ballywallon 1836; died 31 Jan 1855 aged 73; husband of Margaret; father of Robert; buried Ardquin graveyard V17 p 127 OSM; MIs
Samuel DONALDSON . Ballyphilip regd. Portaferry ; husband of Ellen Matthews; father of William b. 3 Jul 1874CR
I stop there, wondering about Samuel possibly born Ballywalter[b~1782]] what do you make of it as I can see you have done your own research.
If Ballywalter connection the current descent of the Mulholland linen family is Lord Dunleath
A Mulholland might have dispatched him to be Bailiff in Ballywallon before 1836 the landlords of portaferry district are listed in each parish see Griffiths. his area of responsibility might have been larger and other Ards parishes included
anyway good luck onwards in your quest
I have more on Tullylish Donaldsons if wanted