I wonder if you still look at this forum? I’ve only just discovered your post, I’m also researching the said James Kincaid (and other spelling variations) on behalf of a friend, who is his 6th Great Grandson.
I have found an apprenticeship record for him, in the Blacksmith’s Company, dated 6 Nov 1740, which gives his birth county as Middlesex, son of Andrew Kincaid of St Giles in the Fields, Victualler to John Dalton.
This was from “London Apprenticeship Abstracts, 1442-1850.
However, I can find no birth or baptism records for him, nor any further information about his father Andrew. The Kincaid surname seems to originate in Scotland. It’s odd that he had no son named Andrew, so it’s possible that the apprenticeship record is for a different James of course.
Regarding his daughter Susannah, (1761-1824), in a transcription of his Will, she was left a pair of silver salts, 4 silver tablespoons and a silver pepper box.
I’d be interested to hear what progress you’ve made since your original post!