Originally Posted by
neo_781
I don't think they need to be on the same reservation. If it is a separate reservation you will have to call. (note - at least that is the case for Gold and higher status so I'm assuming the same for Silver)
Officially you DO need to be on the same PNR. Unofficially, at least higher statuses can get it even when on a separate PNR, but I'm not sure if this goes all the way down to Silver (especially given the extra complication of it being at check-in only)