I doubt that anyone has undertaken systematic research into the origins
and circumstances of immigration of the several Cavitts who arrived in
western Pennsylvania in the first half of the 18th century. Or if
someone has, they have not published it.
One widely repeated, but utterly undocumented story has it that three or
four son of the seven sons of a Moses Cavitt (b1664) came from Scotland
to America at various times prior to 1750 and that, after moving to
Ireland from Scotland, the old man and three teenage sons came in 1750
from Ireland to Pennsylvania to join the others. No daughters of the
senior Moses Cavitt have been mentioned to my knowledge.
The seven sons are supposed to have been: Alexander (b1705), Richard
(b1707), Sheridan (b1710), John (1713-1784), Michael (b1733), Moses
(b1734), Patrick (1735-1835). Obviously, the later sons were born not
born to Moses' first wife.
Patrick youngest of the eight immigrants is said to have had eight
children by an unidentified first wife: Jean (m John Purdy), Michael,
William (unmarried), Margaret (m John McGinnis), John (m Fanny Ewing),
Samuel (m Nelly McLaren), Andrew (served in militia 1776)
and Moses.
Patrick and second wife, Mary Porter, are said to have had three
children: Nancy, James and Richard.
All of the foregoing is from an eminently impeachable source but I pass
it along in the hope that there may be some small scrap of validity
hidden therein which will be of use to you.
Jack Bryan