Swap email address

Hello, Is there a way to swap email for signature blocks? For example: I added '[email protected]' as buyer and '[email protected]' as cobuyer. Now i want to swap these signers. When i try to update the signer information in this case, as the cobuyer email is already present and when i try to update the buyer information with cobuyer information, it is throwing me an error 'Email already in use' as email is unique identifier. Is there a way to swap these two signers? Could you please help me out with this. Thanks, Sushma