Only one cart for all site

Hello to see if anyone can help, thanks in advance.

marketpalce plugin in options, i selected yes on Global Cart option, But when i add product to cart to shop on 1 and i Have Another product on shop 2 (becouse i have mu), i have Each Each product on view cart, a product on cart of shop 1, and Another product on cart of shop 2.
I undestand Global value option is to Cart or use "add to cart" unique product to cart. Regardless of the store in which one does the action, one
shopping cart for all sites.

My desire is that the user regardless of which store to buy, you can select items or products from shops and pay Is this possible?

Thanks in advance for your help.