Map 2 domain names onto one site

I have a multisite setup and wish to map 2 domain names onto one of the sites.

Example, original site location: http://www.mum.com/kidz/

First mapped domain http://www.kidz.info

Second domain to be mapped http://www.boyz.info

I have done this mapping for half a dozen sites, and believe myself have done the DNS stuff correctly.

My problem now is, I found no way the "Domain Mapping" plugin let me input the second domain name.

Any help?