TOPIC: Self unregister

Hello,

I have a soccer team that I am managing.
I want to be able to put all the practices and games into the calendar and register all of the 20 players to each events in advance.
Then, since all the player are already marked as attending, I need each player who won't be there, able to marked themself as non-attending.

Also, is that possible to put all the upcoming event into iphone or Blackberry calendar in one click?

Thanks,

Jean