Notes:

He was the author of a work against Popery entitled The Great Blessing of a Monarchical Government, etc., which was published in 1724, and dedicated to King George I. He voted at several elections of Representative Peers. He (or perhaps his wife) is said to have kept a gaming-table in London.

Family/Spouse: Catherine Launder. Catherine (daughter of Rev Robert Launder) died in Jun 1741. [Group Sheet] [Family Chart]

Notes:

MARY, suo jure Baroness Mordingtoun, assumed the title at her brother's death, on the supposition that the limitation of the patent included heirs- female.
She died 22 July 1791, having married, after 1741, William Weaver, an officer in the Horse Guards, who fought at Dettingen and Fontenoy. He died 28 April 1796, aged over eighty, at Hallow Park, co. Worcester.
Since the death of the Baroness the title has not been claimed, and if the issue of the second Lord then became extinct, the Peerage is now vested in the heir of line of the only daughter of the first Lord, Anne, who was married to Robert, Lord Sempill.

Family/Spouse: William Weaver. William was born before 1717; died on 28 Apr 1796 in Hallow Park, Co. Worcester.. [Group Sheet] [Family Chart]

Notes:

Probably illegitimate

Campbellina married John Jackson on 1 Nov 1755 in Oxford. John was born before 1755; and died. [Group Sheet] [Family Chart]

Notes:

CHARLES, de jure fifth Lord Mordingtoun, but he never assumed the title. He was concerned in the rebellion of 1745, was taken prisoner, and arraigned at Carlisle 11 September 1746, as Charles Douglas, Esq. He
then pleaded his Peerage as heir-male of the body of the second Lord Mordingtoun, and the plea, though opposed by the Crown, seems to have been allowed, without any proof having been required as to the limitation of the dignity being, as he alleged, to the male heir. He appears to have died s.p. certainly before 1791.

Some sources report him to be a brother to the 4th Lord.