Sabrina,
the creation of websitefrom the front-end (Joomly Childs) does not follow exactly the processing that you described.
In JMS, to create a website from the front-end, the user must first be registered and after, you can define a menu entry where the user will enter some parameters to create the slave site.
See the tutorial video 13 that present how to create such service.
www.jms2win.com/tutorial#jms12x-13
So YES you can provide to your users the creation of their own website and hide the installation as you will have setup everything to create such website.