Booking tickets and reservations for our group? Or should everyone buy their own? Make their own ressies?

[kkmcan]

I'm in charge of buying tickets and making reservations for our group of 6 for early November. I had originally planned on doing it for all of us but 2 of our group members may not be able to go when we go and may decide to go with their own family another time. Is that going to be a huge deal if they decide to hold onto their tickets and go another time? Should they book their own for that reason? Is it important for all of us to be booked together?

Thanks for any advice!