William McDonald Ballinderry near Lurgan born 1806/7

Hello I am trying to trace my gg grandfather William Mc Donald. He joined the British  army in Lurgan 1824 (94th regiment which merged with the 96th Regiment a few months later) His enlistment papers stated he was 17 and was from the parish of Ballinderry. He ended up in New Zealand in 1844 with the army, was discharged in 1848 and died in Auckland NZ in 1876. I have been unable to trace any family connection to Ireland . I have been able to trace a DNA connection to the McGoun/ Ruddell families  to Tamnafiglasson , Seagoe , County Armagh. Family notes on a photo stated that William McDonald was Priscilla McGoun's cousin.  Priscilla Ruddell  married James McGoun (Macown) in on 19th Feb 1861 at the Portadown Presbyterian Church. Fathers are listed as John Macoun and John Ruddell. It is listed on a family tree with Priscilla Ruddell's mother was Priscilla McDonald. ( I have not found any documents on Priscilla McDonald). the McGoun family emigrated to New Zealand in 1862 and were in close contact with the McDonald family in New Zealand.

William McDonald married Mary Ann Girvan in 1827  in Stoke Demerol. They had 2 children that I have found Mary Ann 1829 and Samuel 1837. Mary Ann Girvan died in 1840. Samuel travelled with his father to Australia in 1841 and then on to NZ. William married Isabella Lochead in Auckland NZ in 1844 . They had the following children James Skinner ,Elizabeth Hamilton,  George May ,William, Henry Campbell,  Isabella,  Catherine, Priscilla, Jane Barber, Robert John and John

Any assistance in tracing the Irish connection would be gratefully received. 
regards Kathryn O'Neil