If you were completely honest, you'd admit that oodles and gobs of other unknown-to-you people must have been involved.
There are other people involved but, other than the patsy (and the ejected Mac Wallace) it is a list of conspirators who knew what was going to happen that day.
Those who knew there was going to be an assassination attempt.
Georges De Morenschildt has to be involved in some capacity. This known friend and associate of the Byrd family who decides to befriend Oswald. An international man of mystery and flamboyant socialite befriending this hostile, sulking loner living in abject poverty. It is so weird and impossible to leave out. De Morenschildt's testimony reveals that he couldn't stand either of the Oswald's but he keeps having to insist there was something he liked about Lee, and then a few sentences later he'll be talking about something he really disliked about him. It is a genuinely bizarre aspect of this whole story and, although De Morenschildt can't be left out, I'm not 100% sure how he fits in. I just don't need him to have foreknowledge of the assassination.
And then there's Shelley's sidekick, his "Igor", Billy Lovelady. He doesn't have a clue what's going on and just does what he's told, although he keeps almost effing things up because he can't keep his story straight. Lovelady does what he's told to do and says what he's told to say but he has no foreknowledge of the assassination as he couldn't be trusted with that knowledge.
In my made up theory these are the only people who had certain foreknowledge:
LBJ, Byrd, Cason, Shelley and Dougherty.