He is married to Elizabeth Forrester.
They got married on July 14, 1864 at Govan, Lanarkshire, Scotland .Source 1
1864 JENKINS, JOHN, FORRESTER, ELIZABETH (Statutory Registers Marriages 646/1 76) Govan
1864 MCMILLAN, JOHN, MARY FORRESTER (Statutory registers Marriages 644/6 47)
Marriages in the District of Blythswood in the Burgh of Glasgow 1864.
1863 Thirty First December
304 Bath Crescent, Glasgow
After Banns according to the Forms of the United Presbyterian Church
Signed
John McMillan
Boilermaker Journeyman,
Bachelor Age 24
59 Wigton Street, Glasgow
Parents: John McMillan
Shoemaker (deceased)
Janet McMillan
M.S. McNeil
Signed
Mary Forrester
Dressmaker,
Spinster, Age 22
56 Wigton Street, Glasgow
Parents: William Forrester
Engine Keeper
Christina Forrester
M.S. Sim
Signed
John Wilson
Mitchell Church, Glasgow
Signed
John Jenkins, Witness
Elizabeth Forrester, Witness
Registered
1864 January 5th, Glasgow
Gavin Buchanan
Assistant Registrar