I'm planning to visit Japan and then Mongolia in September.
An airline I'm thinking of using to get from Australia to Japan doesn't offer flights to Mongolia itself, though it's possible one of its partner airlines does.
Are there any airline rules against booking a return trip from Japan to Australia, and ordering a return trip with an unrelated airline that goes from Japan to Mongolia and back to Japan? In case it's dependent upon carrier, I'm looking at using JetStar to go from Australia to Japan.
The main concern I have is that the aircraft carrier may look upon it with suspicion in the same way as fuel dumping or hidden city ticketing is.