At the time of the Virginia Peace Convention Virginia wasn't planning on seceding. After Sumter, Virginia had no intention of staying. So what was there to negotiate?
I'd have to disagree. The political powers in Virginia were fully intent on secession but they did not have an excuse or nearly enough support from the population to do so.
The Virginia power structure was firmly committed to disunion long before Lincoln ever took office. And at the same time, Davis and the Confederates of the deep south understood that they could not survive long without Virginia and the upper south, but especially Virginia.