Hello @Mk3nn
First of all, welcome to the TruckersMP forum, and I would like to express my apologies for the issue you are facing.
Unfortunately, in this situation, there is nothing you can do. You cannot access the game until your brother's ban expires.
Even if you do not attempt to do so, the game assumes that you are attempting Ban Evading. Therefore, it does not allow you to play.
§1.2 - Ban Evading - 90 days
Creating or using another account to get around a temporary ban. Evading a permanent ban will result in a permanent ban on all accounts. Attempting to remove ban evidence to get out of a ban. If the evidence points that you have evaded a ban, staff reserve the right to ban you again without notification. Evidence for ban evading cannot be disclosed due to it containing confidential server-side information.
I hope it helps.
Kind Regards,
Mr.Drexyy