Checkout issue with multi stores

[tkovapor]

Hi. I've set up 2 different stores (CE 1.8.1) and with help from the forum and such, all seems to be working fine, except that I need to run all online transactions through one store/URL. So that, whether someone is in store 1 or store 2, all actual checkout processing goes through store 1. Both stores are currently set up through the same Magento website, just with separate stores and store views. Should the website/default config be set for store 1? Do I need to set the Secure URL for store 2 to be the store 1 secure url (both sites do have SSLs already set up)? Do I need to do something with the URL Options-Add Store Code to URLs? Or is it something I need to do in the .htaccess? Something else? All help would be appreciated it.

[Sinisa]

Can you describe how did you set up to use 2 stores on one domain? Did you copied modified index.php into some other directory, and that's how you're approaching to the other store, or not? 

I need more information what have you done in order to help you.

[tkovapor]

I haven't actually set up 2 stores under 1 domain. I've set up 2 stores, with 2 separate domains, under one overall website in Magento.

[tkovapor]

And, as it turns out, I've figured out how I can redirect all sales through one of the checkout areas for both stores (just set the Secure URL's to all be the same across the 'website' no matter which store/view/domain you're using). What I need help trying to share are the customers/Carts. So, how can i set it up so that carts are shared across domains?