One iPad two apple accounts, can we both use iMessage?

Is there a way to have a second set of messages on iMessage? My apple account is the one that is set up on iCloud , but it is the wife's email that is set up on the iPad. When I try and add a second address to the iCloud account it tells me the address is already present but yet it isn't recognised in iMessage as an account! Can iMessage be set up like email with two inboxes? Help