How to have "Add to Cart" button add to specific store when viewing global listings.

I have a MarketPress + WP MultiSite installation using a custom developed FrameMarket Child Theme (based on GridMarket.) I am not using the Global Cart option and instead using a custom function to parse through all carts and display them together on a single page with links to the carts checkout page.

At present, when listing global products (on the main store) the "Add to Cart" button takes the user to the product listing on the specific store it belongs to, where the user than has to click "Add to Cart" again and then has to return to the global products page to add another product.

What I'd like to do is have the "Add to Cart" button automatically add the product to the cart of the store it belongs to directly from the global products listing page.

My reasoning for this is that, as the user can access a single checkout page for all the carts, it feels cumbersome to have them bounced around between stores to add products from the global listings product page.

Has anyone implemented something similar to the above or can advise me as to how to accomplish this?

Thanks!