Business Select passengers are automatically assigned a boarding position. You do need to check-in, but when you check-in has no affect on your boarding position.
Because you have a Business Select fare, your companion will receive no special benefits and must check themselves in 24 hours prior to departure. They will not receive sequential boarding positions or a spot in A1-15. They can purchase upgraded boarding after check-in if you want them to have an A1-15 boarding position.
--TheMiddleSeat
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