Does anyone know if it is possible to link PNRs where I am flying on the same flight but NOT the same itinerary as the other passenger(s)? Reason I'm asking is to see if companion can be upgraded. Example:

Me: BOS-ORD-LAX
Companion(s): ORD-LAX

Given that I am flying on the same flight ORD-LAX, can I upgrade the non-status companion via linking PNRs or other method on that segment?