What happens when you close an Amex Platinum Companion Card/s?

Overview

I recently got a couple of family members the companion card to my Amex plat. It’s the free card that gives them Global Entry spend credited back. My question is - What happens if I close their companion cards (only)? Will it negatively affect their credit? I’m more concerned about theirs. I’m not closing the main Amex plat. I don’t want to sound like a \_\_ but I have exceptional credit and I don’t know if I can help them boost theirs by being tied to mine and it negatively affecting it if I cl

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