You don’t put two people on a panel who are prospective witnesses, unless you’re specifically looking to either invalidate the panel altogether, or pretty much admitting that you don’t want to take part in the panel without saying inasmuch.

For example, if I was in charge of putting together a joint committee on investigating the NFL’s issues with massage therapy, and I appoint DeShawn Watson and Bob Kraft to the committee, it’s pretty clear where my intentions are.