Game center: 2 phones 2 IDs 1 iTunes account?

[Tojasonhoo]

I will be upgrading my iPhone soon and adding a second iPhone to my account. How can I register the second device's ID for game center invites so that it remains separate from mine yet under the same iTunes account?

 

[Tojasonhoo]

?

Anybody? Any thoughts at all? If I register a new apple ID in game center will it affect the phones access to iTunes? Surely many people have multiple devices on one account. Any advice would be helpful. Thanks.