Playing multi player on xbox live

This is probably a really stupid question
but I don't know anything about these consoles
so here it goes.

I have just got my daughter an Xbox and she
is glued to assassins creed.

If she plays Xbox live she can talk to her mates
and they can play the game together as far as I can tell

Can my other daugher join in as I have two controllers
and play off the one box ?

The kids don't know so I am knackered !!

I fear that you cannot play multiplayer in Assasins creed as this is a Role Playing game . But you can play with your daughter from another XBOX . If you have any doubts please let me know .

Cheers ,
Faiz S

Yes it all depends on the game your playing if multiplayer is supported but regardless of any game you are playing you can still do a party chat with your friends.
Check the back of the box for the game to see if multiplayer is supported.