Originally Posted by Mwenenzi

Ugh!!!
You may end with a AS freq flyer account via VX.
Having multiple ffp’s with low balances is never a good idea. You may never get enough ff miles/points to be of use before they expire. FFP’s are for the medium to long term. However at times it makes sense to have a ff membership with an airline in another alliance. (e.g. Oneworld & Star)
http://www.flyertalk.com/forum/miles...-t-expire.html

The airline you fly and the airline freq flyer program you credit those flights to does not need to be the same. That is what ff partners and alliances are about. You can earn ff miles in your ffp flying on other partner airlines.

Cross airline upgrades are not common, but DL & AS have some arrangement (Look in the AS forum)