Just want to be sure I understand the situation. You will making a reservation using your points but you are making a reservation for other people. You will not staying at the hotel but other two people will.

Other two people's name will be on the reservation, isn't it? If such is the case then there should be no problem. It is still common at Japan that non-Japanese will be asked to show a passport (does not happen every single time, but not unusual) at check-in. If two people staying are listed on the reservation then there should be no problem.