Return to Shop with different URLS

Thanks in advance for reading this and any help. We run custom flash stores for different groups, all based out of the same url. 2 examples below.

https://store.battaglias.com/sample/

https://store.battaglias.com/fake/

All of the sites use a universal shopping cart. We are trying to find a button that would return the customer to the unique URL when they are in the shopping cart (not to generic store.battaglias.com).

I am not very tech savvy. Any thoughts? Thanks!

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