In the beginning I played Clash of Clans on my IPhone (I have one account.) After a year my brother played the game on his IPad and IPhone(he has one account, too.) Now we (me and my brother) play clash of clans on 3 devices(two accounts.) I want to play the game on MY Ipad without creating a new apple id. How do you do that without losing my brother's account???
I believe what you are getting at fundamentally is whether you can transfer the progress of a Village from one iOS device to another, but you partially already know the answer because your brother is doing it with his iPhone and iPad. The dilemma is that you both have the same Apple ID, which could present a problem if your Village was tied to your Apple ID. Clash of Clans, like most iOS games actually ties your progress to your GameCenter account (which can be the same as your Apple ID, or can be different). SuperCell gives details of transferring Villages between devices in a FAQ article here.
Based on what you've described, I don't think it is likely that both you and your brother have the same Gamecenter account. You can verify this by opening Settings->Gamecenter on your device and his device and check to see that the accounts that are logged in are not the same. If they were, you'd most likely be playing the same Village across your past 3 devices. Either way, if you want to share a device without conflicts, you'll need unique Gamecenter accounts. On a given device, when you log out of one account and log into the other you should load the other account's Village.
As an aside, Apple doesn't exactly make it easy to switch back and forth constantly between GameCenter accounts. If what you are seeking is just a one time switch to be sure you aren't overwriting each others villages, linking to separate GC accounts will solve your problem. If you are trying to use one device with two villages, you may find that the constant GC account switching is more trouble than it is worth (given that you already have 2-3 other devices in play in this scenario).
First of all are you using the same Apple id? If you are it still doesn't matter, just go into your iPad go into settings in Clash of Clans, click link device and then click
this is my new device. And on your iPhone go to setting in Clash of Clans and click link device but this time click this is my old deviCe. Wait a few seconds and it should be done!