Katherine,4th d. of Sir Patrick did marry Ninian Adair of Kinhilt. Lochryand is probably Lochryan, the estate of the Agnews of Lochryan. It is just north of Stranraer. Gilbert was a family name. Gilbert. G, 2nd son of Andrew Agnew of Lochnaw b. c. 1515/6 was Agnew 1st of Galdenoch, a castle near to Lochnaw. Burgi de Strainraurer means Burgess of Stranraer - in order to trade in a burgh or sell your goods at its market you had to be a burgess. Your Gilbert is probably the one mentioned above as he was in possession of the estate of Galdenoch from about 1574 to 1623. Without knowing what you document is I cannot comment further.