[Ultimate Branding] Able to add multiple codes to Signup Form

I would like to be able to add multiple codes for the 'Signup' Form Module in 'Ultimate Branding'. To allow for the same invite code whether uppercase, lowercase or capitalized. So people can add the code either way and it will accept it:
e.g. asgard, Asgard, ASGARD

At the moment it only allows for just the one code (Letters and numbers only.)
If could add other codes separated by a comma, that would make it more user friendly. Thanks.