Thanks everyone! To complicate matters, my wife created an account that didn't include her middle name because she was rushing to create the account, but I added her as a nominee on my profile with her middle name included and now I can't add her via the pre-filled drop down nominee entry as Passenger Two because of the discrepancy. I'm hoping the seats are still available and just add her manually.

Assuming I can still book the redemption fare, once I add myself and my wife, I'm assuming I call Singapore Airlines again and tell them I'm adding a lap infant, is that correct?