Dr John Boyd's daughter Elizabeth married John Given on 27 Apr 1849 (Coleraine Chronicle); T.H. Mullin says, 'Elizabeth married John Givin of Springbank.' (Coleraine in Modern Times, 1979.) Springbank was not a townland or parish in Ulster, but on Google Earth there is a Springbank Road in the townland of Ballywoodock, parish of Dunboe, Co. Derry, which is south of Downhill Castle ruin. Perhaps there was a Springbank House there where John lived at the time of his marriage. A John Given, gentleman of Portrush, died 29 Feb 1888 at Portrush, where Arabella died in 1884 (PRONI Wills Index). The Boyd heirlooms may have gone to Portrush.
Do you know whether John Given was brother to another of Dr John's sons-in-law, Robert Given, wine merchant of Coleraine? Robert died 16 Oct 1882 -- much richer than Dr John (PRONI Wills Index).