This seems to cause a few issues internally when offers get applied to credit vouchers. I cancelled a flight to HKG in January booked during the DSC offer. I opted for a credit voucher and then wanted the recent 50% bonus SC offer applied to the bookings under the voucher. It slipped my mind to even ask if the DSC offer could apply to these flights. In the end, I got a few different responses but ultimately I emailed the Qantas team who said to contact them after my flying had been done so they could ensure SCs got credited correctly (e.g. 50% bonus) and that they would honour the offer.
As such, I would be very interested in the outcome of this as my SC earn could increase by 25%.
Let us know what the P1 team advises.