I am using the plugin wp-multi-network(http://wordpress.org/extend/plugins/wp-multi-network/) to maintain child networks under multi site.Using this I can create child networks.But I can’t set sign up functionality to child networks .And If the main network is **mainnetwork.com** and **childnetwork** has the domain like **childnetwork**. mainnetwork.com .The sites set under this child network would not get the domain as site. childnetwork. mainnetwork.com  .

Does any body have Ideas to get these functionalities? And does any one w’d like to share your experience and the knowledge you have with this plugin? 

(I got got answers by my self and updating the topic .So it may be useful to others)
The child networks **childnetwork1. mainnetwork.com** and **childnetwork2. mainnetwork.com** also should have the sign up functionality .If I want to give a complete access on **childnetwork1. mainnetwork.com** to a person 'X' or group "X group" .X can able to use it as his own blog network and he can let others to create blogs same as me.So I still  have control on that child network and at the same time X acts as super admin for the blog network.

The basic purpose of the wp-multi-network plugin is the same.Presently one cannot able to set signup functionality to child networks .But Admin of child netoworks as well as the super admin can create sub-sites under child networks from their **dashboards** .
       So this a multisite can be used as network of networks .