Multi-store - getting contents of two carts

[Silver Rocket]

prestashop 1.6
 

I am working on a multi store site which has separate carts. 
 

in order to notify a user if they attempt to switch stores with products in their cart from another store, I need to be able to get the products in the cart for both carts. 
 

the page that does this check is in store ID 1, and even setting the context I cannot get the products of the cart from store ID 5. 
 

I am needing to get the contents of these two carts in the block cart controller and these are then set in JS variable which are utilised in a JS file. 
 

any ideas welcomed! Thanks