Editions: Daedalus Balance Check
You can use 1 Rewards wallet to receive funds from all of your Balance wallets in Daedalus Balance Check.
Say you have 3 Balance wallets. You have restored all 3 balance wallets in Daedalus Balance Check. You get prompted to Move testnet ada (1 in the screenshot below) for each Balance wallet.
If you do not have a Rewards wallet, you will have to create one as part of the process of moving your funds. See Preparing your testnet ada for staking
If you already have a rewards wallet then you can simply select the Rewards wallet you already have and transfer your ada to that wallet.
Note that for this example the Rewards wallet is named "Rewards wallet" Of course you can name your wallet anything you like.
Using this method you can consolidate all your Incentivised Testnet ada into one rewards wallet if you want. You just use the same wizard and always select the same target Rewards wallet. It's as easy as 123.