Are you able to add more than one person to play online on the same system. Also when you add a friend into your game how do you add them tot he same game that you are in.

You can create subaccounts so that different people in your household can play online with different gamertags (each user must have a different email address to use for the account), but not at the same time as Lydon said.

I have heard that you can add friends into games while they are ongoing if the game is not full, but this has never worked for me. Best way I have found to join up with friends is to sit in the main lobby and send them party invites once you see they are online and wait till they join your party, then whoever sent the invite to start the party is in control of picking the games (team only games once you are partied up) for the party to play. You can also play private match with custom game settings against ur friends, but those games don't count toward any online stats (XP, kills, etc.).

adding friens is done via private match then invite or even just while in another game (not advisable) or in lobby just on invite friend