Robert was born about 1725, the son of unknown parents. The place is not known.
His wife is not known. They were married, but the date and place have not been found. Their only known child was Margaret (c1740-?).
Genealogical History and Pedegree of the Family Montgopmery, Compiled by Thomas Harrison Montgomery, printed for private Circulation 1863, page 148.
MONTGOMERYS OF STANHOPE, BARONETS.
Sir James Montgomery, Baronet, of Stanhope,' county Peebles, was
second son of William Montgomerie of Macbie Hill . He
was Chief Baron of the Exchequer in Scotland, in 1775, and Member of
Parliament for Peebles ; and was created a Baronet, July 16, 1801. He
married Margaret, only daughter and heiress of Robert Scott of Killearn,