Product Header Change Depending On Vendor

Hello,

Each of my vendors have a separate inventory.

I have modified my theme so that my site is separate from the vendor sites; I have no products, the vendors do. The problem I am facing is that when a customer is on my branded vendor page which displays the vendors products, the customer clicks on a product and suddenly is on my branded page.

I would like the vendor header to remain for the vendor products. I would prefer it to remain throughout the entire checkout process as well, if that was possible.

Any pointers out there? I'm new to cs cart but seasoned with other shopping cart systems.