I have tried searching the threads and too many hits forces me to ask this questions...

I recall somewhere that it is possible to earn miles on one airline while fying on another.

My wife wants to go to LAX from MCO next month and UA has flights for a good price, the Delta flight is $125 more than the UA flight but my wife does not want to spend the extra to get the MQM miles from Delta.

She was recently give Silver Status even though she only had 24,600 miles (lucky her). So I want her to contniue to maintain elite status since we have missed out on First Class several times since she was not an elite member.

Any help would be appreciated and thanks in advance.