We need to do a few things. Here is whats needed.
We need to create a login area within our existing website. Here we need to be able to create a username and password for the customer we need a super admin area where we can give permissions for the users.
We then need to install a viewer into the client area where they will be able to view files such as excel and word documents. I was thinking something like zoho sheet. its important that it doesn't have a brand such as zoho sheet on the viewer when my clients log in.
We need to create a scrip on our in house small business server (windows) where we can tell the viewer what is to be shown in the client area.
We would have a folder on the small business server, and we could create a folder with in a viewer folder. This would then allow a particular user to view particular files with in these folders.
So what im trying to say is different users will see different files.
We need the updates to refresh in real time so if some one makes a change to the file the customer that is logged in will see the change in real time.
To do this project you would need to be able too do the web server login area as well as the script that would view the files in real time form our small business server.