Multiplayer Offline Dynasty on one Xbox360?

[Bigfoot365]

Is it possible to play an offline dynasty with multiple users on the same 360? I would like to play a dynasty with my son, so I created a dynasty with two human-controlled teams. However, when he logs in with his user he cannot load the dynasty file. I guess I could just have him use my login any time he wants to play a game, but we generally play with a few different settings (I use QB auto-throw and he does not, for example) and I would rather not have to keep changing them. Also he would like to get his own achievements.

I tried setting up an online dynasty, but after a week or so he is now locked out and EA wants him to purchase an online pass just so we can play each other. EDIT - somehow he can now access the online dynasty, but I would still prefer to play an offline dynasty because of the server issues.

Is there any way around this?