My question is really an extension of a previous question that was ported from stackoverflow and closed so I cannot edit it. The basic gist is a regional franchise company has decided to force all independent stores into one website look; they currently all have their own domains and completely different websites. After reading the helpful answers and looking over some links provided, I think my solution is to put a 301 on each franchise store site (acme-store1.com, acme-store2.com, etc) back to the main corporate site (acme.com). All of the company history, product info, etc (about 90% of the entire site) applies to all stores. However, each store should have some exclusive content such as staff, location pictures, exclusive events and promotions, etc. I originally thought that I would simply do something like acme.com/store1/staff, acme.com/store2/staff, etc for the store exclusive content and then acme.com/our-company, for example, would cover all stores. However, I now see two issues that I don't know how to solve.

1. They want to see site stats based on what store site they came from. If a user comes from acme-store1.com, is redirected to acme.com and hits several pages, don't I need to somehow keep that original site in the new url to track each page in that user's session and show they originally came from acme-store1.com?
2. Each store is still independently owned and is essentially still in competition with the other stores, albeit, in less competition than they are with other brands. This is important because each store would like THEIR contact info, links to their social media pages, their mailing list sign-up and customer requests on EVERY page. So if a user originally goes to acme-store1.com and is redirected to acme.com, it still should look to the user that it's all about store 1, even though 90% of the content will be exactly the same as it is in the store 2, store 3 and corporate site. For example, acme.com/our-company would have the same company history, same header/footer/navigation, BUT depending on the original site the user came from, it would display contact and links to THAT store. If someone came directly to the corporate site, it would display their contact and links (they have their own as well).

I was considering that all redirects would be to store1.acme.com, store2.acme.com, etc (or acme.com/store1) and then I can dynamically add the contact info and appropriate links based on the subdomain or subfolder. But, then I have to worry about duplicate content penalties because, again, about 90% of the text in these "subdomains" are all the same. For reference, this is a PHP5 site. I've already written a compact framework utilizing templates and mod-rewrite that I've used for other sites. Is this an easy fix that I'm just not grasping? Any suggestions?