Originally Posted by
woodenshoe101
To preferred seats, yes, but not to C+ (which are also preferred seats, but different rules).
For C+, with more than 1 companion, everyone on the PNR needs to be a medallion member, and everyone on the PNR defaults to the lowest tier medallion status in the PNR for upgrade priority. If one on the PNR is general member, everyone is out of luck unless you split off reservations.
I was responding to previous poster question on whether or not Preferred Seating was available when you have more than 1 companion on PNR (context now added). The situation with C+ upgrades has already been well covered in thread.