Originally Posted by
Bruin1K
New rule and happened to me too. Only exception is Lufthansa
It is absolutely not a rule.
Go to united.com right now and search for flights BKK-SIN or BOG-CTG (or MDE or CLO). Those are just a handful of examples (that I am particularly familiar with) where UA will sell 100% non-UA, non-codeshare itineraries.