In airports where SP is "humanly" enforced (like CDG), you won't have an issue bringing your friend/colleague with you, including at the boarding gate (just say "he/she's with me" when they check the BP) - at least never had an issue before.

Some airports (like GVA, or BRU from what I just read) will have "automatic" doors for SP passengers. In that case, kindly ask the desk agent to update the boarding pass of your colleague. Tbh, I only had to do it in GVA once, and it worked fine. I agree that because they "can" do it, doesn' mean they "will" do it.