SOrry for "email me". I meant "if you are able to make this happen, if you are interested in being hired for this project, then email me". I am an entrepeneur, not a coder.
Yes it's multiple domain names.
I wrote multiple installations because I learned that Magento doesn't allow multiple vendors (multiple admins for specific store).
This is the project...
I am the server, e-commerce solution and Products (books) DB provider/maintainer who will sell a complete e.commerce system (store) to my clients who are already buying my product DB in a different format. So I need to give full admin to my clients to their own store. Each store admin will be able to manage their own product DB. Every store will display BOTH products from my DB (the shared one) and their own pvt products DB.
I have taken a look at the extension you suggested, for which I thank you, but I will email them to make sure their extension does the job. It looks like it's the right solution.