How to handle body language and the use of subtle signals

We came across a situation in my game last night that really pushed us for a novel solution.

My character, Kwaarem, and another PC, Vincent, are talking to an NPC, Joren. Vincent wants information from Joren that implicates me in a conspiracy (and would not please Vincent). After Vincent asks his question, I say, “Tell the truth, Joren,” but I mouth, “No,” and try to subtly nod my head, “No.”

There are multiple parts to this.
One part is the communication of unspoken body language to Joren. We had a really rough time figuring out what an appropriate test would be. I’m also wondering whether there’s one test for me communicate and then a linked Observation test for the other character to dig where I’m coming from.
A second part is trying to be noticed only by the character I want to notice me. Is this an Inconspicuous?

Are these two totally independent? We boiled it down to one roll, but I’m not sure that was right. My succeed/fail at the getting my point across is independent of sneaking it past someone else, right?

You need to back out a bit and think of the basics here. Who has an intent?

Vincent: Wants Joren to give some information.
Kwaarem: Wants Joren to lie.
Joren: is an NPC, so doesn’t have an intent really

That to me sounds like a versus test between Vincent and Kwaarem, probably Persuasion. The subtle body language would be a FoRK from Inconspicuous.