: Tom, I don't pretend to be an expert in these matters.
: From research it would appear John Caldwell and family
: that were immigrants to Delaware and Pennsylvania,
: supposedly in 1727 were Presbyterians before setting
: foot on American soil. He, John Caldwell, was sent
: by the Presbyterian Church, to help the Presbyterians
: get a "foot hold" in the New World. From
: research it
: appears his Caldwell family had been in Northern Ireland
: for several generations. Who knows at what point they
: became Presbyterian.

: At some point in time my lineage of Caldwells became
: Primitive Baptists sometime in the late 1700's or early
: 1800's. This was at some point when they migrated from
: Virginia to Georgia, and David Caldwell and wife Mary
: Elizabeth Tanner Caldwell were in Georgia by 1810.
: When ancestor, Matthew Tanner Caldwell and family
: migrated to Arkansas (1859) the family were still of
: the Primitive Baptist faith. David Caldwell's son,
: Creed Caldwell was an elder as was my great grandfather,
: George W. Caldwell I. As there were no Primitive Baptist
: Churches nearby when my grandfather, John Elijah Caldwell
: and family moved to Louisiana, the family became of the
: Baptist faith (Southern). Most descendents are still
: Baptist.

: Circumstances at each time period probably did instigate
: changes in choices of faith.

: Gwen

Gwen
People do change the allegiance to specific churches for various reasons, incuding the non-availability of a place of worship in their chosen denomination (as in your family). There are other quite obvious reasons also.
I do think it would be highly unlikely that a member of the Castle Caldwell family - known to be Anglicans - would be sent by the Presbyterian Church to propagate that denomination in the USA.
Most Caldwell's in Ireland were Presbyterians and there would be many of that denomination eminently suitable for the purposes of the church.
I do note that the Caldwell family has joined the churches of many denominations and it is (obviously) not an exclusively Presbyterian family.
Scotland is a predominately Presbyterian country and the profession of the denomination of Presbyterian is nothing more than a clue pointing towards Scotland as the original ancestral home.
The point I was making was that the Castle Caldwell family was relatively unique in its adoption of Anglicanism. Consequently having Caldwell ancestors who were Anglican can help assist the researcher by pointing towards either the Castle Caldwell family or the English branch of the family. It also could mean that a Presbyterian Caldwell married an Anglican lady and their family adopted that denomination or, more simply, the closest church was Anglican.
When I was young and living in (Old) South Wales I often went to Baptist Churches with friends even though our family was nominally Presbyterian. As far as I know there was only one Presbyterian Church in a city of 250,000 people.
Tom