Alexander and Mary MacMillan lived in Great Marlow, the County of Bucks, England. In the late 1700s, Alexander came to Prince Edward Island and on the 30 April 1788, was granted five hundred acres in Lot 57 by Walter Patterson, Esquire. In 1797, he returned to England and left his estate in the care of Robert Lee, who was proceeded by George Wright from 1800 to 1819. By 1802, a disagreement had arisen between Lord Selkirk and McMillan regarding this land, which was not settled until 1820. Alexander McMillan, "the elder" died on the 2 July 1831. In his will, dated the 25 November 1830, Alexander left all of his estate on PEI to his son, Alexander McMillan.

The year of Alexander "the younger" MacMillan's arrival in PEI is not known. He married Mary Murphy, and they had at least one son, also called Alexander. Alexander "the younger" died on the 30 June 1861.

A son of Mr. and Mrs. Thomas MacMillan of Charlottetown, PEI, Joseph MacMillan is a descendant of Alexander MacMillan. He graduated from St. Dunstans University with his BA in 1926, and continued his education by obtaining a BSC from St. Francis Xavier University, MA from Laval University, as well as his MD and CM from McGill University. Joseph returned to Charlottetown to set up his surgical practice, and while doing so, also helped to establish the Charlottetown Clinic. Joseph married Eileen D. McQuaid and they had six xhildren: Colin, Eileen, Charles, Thomas, Maura, and John.