Admin should assign IP address for reseller (you've done this already). Reseller can then share the IP, it makes IP shared (you've done this already). Now you can modify the user and assign additional IP to the user.
We made it.. Thanks for your patience.. Big Thanks....
I pointed the IP to one of the domains. I am using Cloudns for DNS and Custom Nameservers.
Trying to go to site in browser, displays this error: (This IP is not shared with any other domain)
This IP is being shared among many domains.
To view the domain you are looking for, simply enter the domain name in the location bar of your web browser.