Making palette discussions useful at a clothing swap

[Liamrab]

Our team is updating the staff portraits, and I have been asked to choose two background colors before the photographer arrives. We have time to test this properly before the booking is finalized. The current gray backdrop makes some faces look unusually pale in the proofs. I would prefer a small printed comparison before committing to the final background materials. People are bringing their usual work clothes, which makes a shared clothing palette impractical. I have been reading about personal color analysis but I am unsure how much that helps when choosing a background for a group. Should we include a neutral reference card when photographing each of the background samples? The photographer can keep exposure and lighting fixed during a short test session. What simple comparison procedure would you suggest before we approve the final background colors?