Good to hear from you. I have some information on Archibald but haven't made the connection either. I am relatively certain that John Cassady was the son of James Casady and Catherine Montgomery. There is a monument in Kingsey Falls that indicates James and Catherine had a son, Alexander married to Catherine Elliott. Alexander and Catherine had a son, Edmund Hanning Cassady and there was a Hanning Cassady that was a nephew of John and a witness at his funeral. I am making a big assumption but if Hanning was the same Edmund Hanning Cassady, that would make John and Alexander brothers. I haven't been able to find any documentation to verify this.
I would appreciate any information you have and my e-mail address is email@example.com
I will gladly share what I have been able to put together.