How can I found out how much? PUTPAC? Any better options than using UA miles for *A partner airlines from Europe?
Might be able to figure it out from Matrix. But best is PUTPAC.
OZ is only 25k (but only an SPG transfer partner, so technically 20k). Not sure what / if they charge for YQ. Although it can take 1-2 weeks for the points to transfer.
If that's not an option, then if SQ is low or no YQ, book with SQ. Otherwise, with UA.