I've heard the term back to back ticketing thrown around ... is the below case an example? This is all for work related trips, and our travel desk said it was okay, but just to be safe.

I'm originally from NYC but currently in Vienna (VIE) for work - flew in on Swiss Monday and have a Lufthansa flight back to NYC on August 31 of this year. However, I have to go to NYC for two weeks in end of June; instead of moving that flight, I just booked a new ticket on SAS/OS, round-trip VIE to EWR (with one stop both ways).

Is it back-to-back ticketing to have a round-trip VIE to NYC flight in-between my existing round trip on LX/LH? Or, since separate companies / all tickets will be used, it's okay? The fare difference + change fee was going to amount to $5K (I'm in J), and the travel desk said it was okay / legal to just book a new round-trip out of VIE since I'll still keep / use my LH flight on 8/31.

Thanks!