Reserves Question

[Phizant]

Ok, so I used to play planetside, and have given the account to my brother. He now uses the account. My question is: Can I use reserves to play with him using the full version of the game, or do I need to install the reserves on my HD. I still use the account when he doesnt play, so i need the full version on my comp....but I do want to be able to team up with him. And when I log in my new name, i cant play without paying. Is there any way to fix this?

Thanks,
Phiz.