creating sub sites under a mapped domain on a Multi site

Hi I have created a Multi Site mmtblogger.com and have mapped a domain stevepershall.com to the multi site platform now what I want to know is it possible to create sub sites on a mapped domain such as
stevepershall.com/shoes and have the domain act like a independent site from stevepershall.com with its own theme and plugins and it would be all running on the Multi Site MMTblogger.com
also only allowing the owner of stevepershall.com to create a new site under the domain stevepershall.com

not sure if this made any sense however this is how I see it working

thanks
steve