Allow user to create new blogs?

To start, please forgive/correct me if my terminology is incorrect. I am new to WPMU lingo and am trying to learn. I'm not sure if this is a common request or something very rare and unique to my service. I run a site where I license a certain online service and offer it to screen printers and entrepreneurs in American cities. Each 'licensee' gets his own location and unique area of my site. In the next couple months I am going to have my programming team take my entire system and create a wordpress plugin out of it so I can utilize WPMU/multi-site to allow advanced customizations and plugin abilities to my licensees. Each 'location' will be it's own WP site in the MU network (are these considered child sites?). I just purchased the WPMUdev package and can't wait to offer the different plugins and resources to my users. I'm wondering if it would be possible to allow my licensee the ability to create their own sub-locations (instances of WP) from their child locations. That way they could setup custom shops (using shopperpress for example) for certain special clients or sales people inside their own locations. So I guess I'm asking if it's possible for me to act as the main admin and create/provide privileges to a network of sub-users. These sub-users would be granted access to control and manager their own WP site/location. Would it be possible for me to allow these sub-users to create their own new WP sites/locations from their sub-locations? Almost like a child of a child? If this is possible, what type of control do I have over these sub-user abilities (as the admin) and what, if any, action would be required on my end for them to successfully create their own grandchild locations (now i'm 100% sure that lingo is wrong! --- Thanks so much for your help!