Book a Shinkansen with Exchange Order

Hello Daniel and all

I am aware that one can only book a Shinkansen 1 month before travel plans. Coming from Australia, if I have paid for a JR Pass and have only been sent out an Exchange Order, and I won’t receive the actual JR Pass and activate it until I arrive in Japan, can I use the Exchange Order to book reserved seats on the Green Car online or using the SmartEx app . If not , is there a way to let Shinkansen bookings know I have already paid for a JR Pass and it is pending until I arrive in Japan so I can book reserved seats.

Many thanks again

Kind regards
Gilb