Only info I have on her father, David Mitchell, is that he was a "Covenanter Elder", likely from the Pequea, PA area where Humphrey 3rd was born. It appears that the Fullerton home was used to deliver the religious services as a note I have is:
"The Rev. John Cuthbertson, a Scotch Covenanter, the first to ever preach in this country came in 1750 or 1751 and went direct to Humphrey Fullerton's home. He preached often at his home and later at the home of his son, Humphrey Fullerton 3rd."
Their first son born in 1773 was named after her father, "David Fullerton".
I am unable to locate any other info on "Daniel Clark, London Merchant".