it is definitely possible to use some tactics to bypass married segment inventory restrictions.

for instance, this itinerary is bookable for $500 on Priceline
https://www.google.com/flights?gl=us...890*.USD.49890

AMEXTravel.com used to work as well, before the Expedia takeover.

And Delta international reissues desk definitely has the power to force a segment into Z, if you can come up with a plausible enough excuse. For instance, ticketed segment1 in Z via DL.com and call in to add segment2, also in Z and say “that’s weird, i must be holding the last Z seat already on segment 1, so can you manually force it to Z.”

the purpose of my thread is not to hear the rule, rather to hear the hacks, like above. you know, something actually useful.