Someone is flying Y (paid by company). Then SQ offer upgrade to PE for $350 within 3 days of flight . (12 hours flight). He accepted it.

during check in, he ask to upgrade to business class using miles. He was quoted 92500 miles which is the rate from Y to J. And the $350 paid will not be refundable.

so if u wan to try to upgrade using miles during check in, do not accept the mySQupgrade.