In the scenario you have described, rather than ending up with orphan QR miles that sounds like they would be of dubious value to you, i would just credit the mileage direct to your UA MP accounts where they are much more useable as *A awards.

Be warned, now that you have joined Privilege club, at every point, (ie, initial booking, online check in, airport check in etc) your booking will revert to your qmiles number rather than any alternative carrier that you supply. So make sure your boarding pass has your UA number printed on it, and double check at every opportunity, that your mileage is going to UA..!

Even then, it only works 50% of the time and you may need to write in with the hard copy of your boarding pass showing your UA number not your Qmiles number and request the mileage be credited to UA.

If you decide to go for the QR miles you will get 17,391 miles each way if you booked in D (discount business) 23,188 if you booked C or J

There is a handy calculator on the qmiles website here that gives you the earning and redeeming combinations on QR. Personal experience is that QR redemptions are quite easy to redeem with good availability but that mileage requirements are quite high, one redeeming feature is they do allow one way awards if you have enough miles for OW with QR and back on another carrier

http://www.qatarairways.com/privileg...ator-earn.html