There are approximately 84 agreements. I've never seen one that parents are not included. (edit: I just checked about 20 carriers, Air France, Cathay Pacific, Lufthansa, KLM, and Quantas don't allow parents. There are still options to Europe, but Australia would have to be on Emirates or Etihad) You can designate a travel companion in lieu of a spouse. Travel companions have access to about 30% of the carriers. Domestically, we have agreements with all the biggies except the Big D. There's enough variety to get you anywhere in the world.