Install MU in subdomain and host sites as subdirectories

Hello,

I’m installing core MU in a subdomain:

https://mysubdomain.mywebsite.com

I would like all of the additional sites to show up as a subdirectory:

https://mysubdomain.mywebsite.com/site1/
https://mysubdomain.mywebsite.com/site2/
https://mysubdomain.mywebsite.com/site3/

Is this possible within the current setup? I’m able to get the initial MU install to work in the subdomain (https://mysubdomain.mywebsite.com), but any additional sites also default to display as a subdomain (https://site1.mywebsite.com).

Any help is appreciated.

thanks!