Chromakey Mask on 2dPlane

Hello! New to UE, starting to deal with some Chromakey inside UE. The my issue is how to mask the area which is on 2 D plane so this are ais not to be keyed out?
Please check screenshot attached- we have virtual studio where we have a real TV screen operationg showing some media reels. But these reels have some green colors aswell. So if we apply Chromakey on whole studio background then the areas within TV screen also got keyed out. So i suppose of using some kind of mask to cover the TV screen rectangle . How it can be made inside the UE? Our current setup is: In our tests we have a default Virtual Production template loaded and then just added a Plane on which the input Live video is placed as Material. Chain is : BMD Media Input> Media Player> Media Player Material> Media Player Material placed on Plane>Chromakey added on Media Player Material > BMD output.