I am a Caldwell also, and wonder if we have a connection. My Great Grandfather Hugh Caldwell came from Glasgow, Scotland about 188? and settled in Peterborough County, Canada.
The picture shows my grandparents and uncle. Joseph Caldwell arrived in PA from Derry, Ireland sometime after c1760. My line derived from James who was born that year in Derry. James married Sarah Byram whose lineage goes back to John Alden of The Mayflower, explaining my uncle’s first name. Some of James siblings headed south to VA and TN. If you are Scots-Irish Presbyterian with first immigrant ancestors from around Pittsburgh, then you may be related.