Originally Posted by
Stripe
I have done this a couple of times without a problem on NW:
Ticket 1: AUS-MSP-DTW on day A, DTW-AUS on day B.
Ticket 2: DTW-AUS later on day A, AUS-DTW earlier on day B.
Ticket 2 is entirely within ticket 1. The only difference is that I had a companion on ticket 2.
I believe this type of nesting is forbidden. Consider you are lucky that it did not cause trouble for you.
OTOH, if your ticket 2 is DTW to somewhere else then back to DTW, then it is not a violation of rules.