Once the first coupon has been used, by boarding, you should them be able to check-in with the second carrier -- at least in a normal situation.
I was under the impression WN could not be on 016 ticket stock nor could UA be on 526 ticket.
We speak of PNRs having a single ticket per passenger but not always
Suspect you may have a PNR with multiple tickets (but then you should be able to check-in with) and this
Can you see the ticket in your UA account? Likewise for the WN ticket?
Going to need a travel agent type to explain this one
Last edited by WineCountryUA; Apr 17, 2022 at 11:45 pm
Reason: 016 not 106 :(