Hey! Sorry it took me too long to get to this. That men who attended both events kept slaves is well known. Body servants, like George Washington's Billy Lee, were generally responsible for dressing and grooming their masters. As such, they would have attended on the delegates in their rooms - rented spaces scattered around Philadelphia - before they went to the State House/Independence Hall.

I know this bends our rules a little bit, but I was at Independence Hall today and asked my guide about this question. He said that, since the Continental Congress and especially the Constitutional Convention were closed-door meetings, slaves and servants would not have been allowed inside the chamber. Delegates who needed something would have to remove to the hall outside.

I don't know if I fully believe him. SOMEONE had to staff the building, and bring these guys water (or alcohol), as sessions stretched on for hours and the chamber was notoriously hot.