Your last paragraph confuses me. I'm not sure who you are talking about. The Julian "Julia" West I have in my data base was the daughter of Nathaniel Spence West. I do not have any descendants for her. She was unmarried when he wrote his will in 1780 but he does not say she is underage so I would put her age between 1759 - 1766 (just an estimate). You seem to be talking about a much later Julia.
There is no doubt who the father of Nathaniel Spence West was. He was Edward West. There is much proof in court and land deeds in both Accomack and Northampton Counties VA. My information comes from actual records. Not that it's proof but Nathaniel Spence West named his first son, Edward.
When Nathaniel Spence West's son, Edward, wrote his will in 1807, one of the witnesses was a Julia Allen. I suspect this was his sister, Julia.
I would like to see your info on Rebecca and her daughter Julia along with whatever proof you may have. I'm not sure who you are saying is the wife of William Warden but if they descend from Nathaniel Spence West, I am very interested. Any format you wish to use is fine with me.