Cleland Familly

I am trying to find any information on the whereabouts of the graves of James Cleland who died in 1777 and his wife Sarah born Baird.  His estate passed to his nephew James Dowsett Rose Cleland.  His sister Agnes born Cleland, was married firstly to Richard Rose, and secondly to William Nicholson whose estates passed to his Nephew William Nicholson Steele Nicholson,  whose daughter Elizabeth married James Dowsett Rose Cleland, and finally Patrick Cleland , who married Mary  Whyte.  Patrick's estates also eventually passed to James Rose Cleland.  Are there any records of all the burials at Bangor Abbey.  Any information would be greatly appreciated.

Kind regards, Judy