Alexander Mcgill and Jean Livingston had a daughter who was born 27 Nov 1809 at Loudoun, Ayr, Scotland whose name was Grizzel Mcgill. Jean Mcgill was born 4 Apr 1813 at Loudoun, Ayr, Scotland. William and Elizabeth were both born on 22 Mar 1815, also at Loudoun, Ayr, Scotland.
There was a William Mcgill born in Scotland in 1815 who married Jane E. who was b. in England. In the 1880 US Census, they lived in Vallejo, Solano, California. In 1850 US Census, William Mcgill and Jane E. were at West Farms, Westchester, NY.
An Elizabeth Mcgill was in the 1880 US Census with Samuel Mcgill and son, Richard 15y, born TX. All living in Peru, Dubuque, Iowa.