I am trying to create a dual purpose site whereby pricing is displayed all the time but Enable_Cart is OFF by default unless a customer logs in as a specific Customer Group.  ie Consumers have prices, but cannot see any ‘Add to Cart’ buttons and Wholesale (logged in customers) see Special prices and DO have ‘Add to Cart’ buttons.

I can see from the code that there is a variable set in the template files as:
$tbData->common['checkout_enabled'];  but I cannot locate where this is originally set. I would like to add some logic at it’s source to take into account the Customer Group Id.

I have years of PHP experience, so I simply need to be pointed at the correct file OR the recommended technique for making this change.

(I know that I could simply add logic to the various template pages that can show the ‘Add to Cart’ button but I would prefer to update the object at source to make this update more ‘clean’.