Sharing an account isn't allowed. As you pointed out, it leads to an inaccurate rating and therefore to unfair matchups.
You and your brother should each maintain separate accounts. You shouldn't play each other unless you are playing unrated games as long as you are located at the same IP address.
Hello chess.com,
First let me quickly say I'm quite a new member here, first-time poster, I'm really liking the site and I'm really enjoying playing chess again but I've got a few questions about Account sharing.
A couple days ago my Brother came to stay with me for a bit and instead of him DEMOLISHING me everytime we play I suggested we play together online as the Timed Game element is new to us because we never played with clocks before and it's a whole new dimension to the game for me - knowing you've got the advantage but your short on time and need to win quick and vice versa!
Anyways, now I'm on a bit of a winning streak and it feels a little unfair because my opponent is obviously now playing two people and my rating, which was about 1100 is now 1500 and my account is now winning tournaments!
I thought about opening a new account for my Brother but we're still going to play together on the same team so it's still unfair on our opponent.
Is there an option for a "Group Account"? Or some icon or special game option I can tick to keep things all nice and open?
I hope this doesn't break and kind of Terms & Conditions Chess.com has got because we're really enjoying our time together here...and I'm especially loving the feel of winning, ... and hopefully learning a little too
Any comments, opinions, links, advice welcomed
Thanks