Sorry, it's not easy to understand everything, if I create a new account, I have to get out of my league with my current account and no longer use it, right ?
Yes, there are even manager with 3 accounts and more. It's just considered bad manners to have more than one team racing in the same league and tier but I don't know if it's actually forbidden as such. Best thing would be to race in different leagues altogether, makes sense anyway since it's quite hard to manage two teams well at the same time.
