For any partner airline besides AF, KLM, or Alitalia, you'll be relying on some third-party source of availability data, whether that is KVS, ExpertFlyer, a partner website, or DL RES. There are many here who can probably shed more light on hunting down availability for specific partners better than I can, with guidance on the best sources and the fare classes to seek out. For VA, I know there was a very well written thread that I can't locate at the moment...