Segmenting Squarespace site for different users

Hi,

Total novice when it comes to coding, and have hit a brick wall with what I want my site to do.

Here's my objective: 

I want let different groups of users access different groups of pages - branded and specific to them, whilst hiding other pages which are not.

What I've tried so far:

- Putting a password on a landing page and then linking to non-passworded pages, but the non-passworded pages are obviously still searchable, so not exactly 'hidden' 

- Created a site-wide password, but cannot see an option to select certain pages which are exempt from this - code maybe?

- Utilisiing customer accounts - this just stores purchase info, rather than giving permissions to different areas of the site (confirmed by SQ help)

- Looked into whether I can create a separate site/template and attach it to part of my original domain, in other words having two separate templates from one domain, one from yoursite.com, the other from yoursite/newpage.com for example - not had any success finding out whether this is possible

Does anyone know, if any of the above is possible? Is there a quick piece of code OI can insert into pages I want to be exempt from site wide password, if I can attach multiple templates to one domain? And, of course, if there is a better way to achieve what I want to achieve.

Any help would be greatly appreciated.