5% from the gross income

I want to start a project with my brother.
My question is if he accepts the user agreement for using the UE4, which says that if you exceed 3.000$ per quarter you need to pay 5% from your income gross, if I make another account so I can help him and accept the same user agreement will we be charged a total of 10% from our gross even if we work on the same project?
Do I need to check something that says that I am working on the same project and do I need to install from my brother’s account the UE4?