RR are for the individual, you won't be able to use yours on his, and you probably figured out. It could cause issues at check in and boarding if he has any special designations such as A status and check in early, it could possibly impact you there as well; In addition it won't show up in his SW account to check in and get boarding pass, and won't earn miles. I had mistakenly assigned the wrong RR numbers to my daughters frequent passenger profiles in my account and this kept happening and I couldn't figure out where it was coming from, then realized I needed to update the frequent flier profiles in my account. Customer service can definitely change it for them and I would do that before your flight.
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