Multiple reservations for the same train?

Hello, my situation is as follows...
I will be travelling solo for about a week, before 2 of my friends arrive in Japan. Each one of us has a JR pass, and would like to use the Sunrise sleeper train. We understand that the Sunrise may be booked out especially the nobi-nobi seats.

Would I be allowed to make multiple reservations on the same train for the 3 of us using my JR Pass? If the Midori-no-madoguchi personnel rejects me (I speak Japanese and will be able to explain the situation, but whether it is acceptable, I do not know), would they know if I visit another station to make another reservation on the same train? We do not mind sleeping separately from each other.

Regards,