Metadata for ACF Relationship fields

I am using the ACF Relationship field to set up a many-to-many relationship between two custom post types (one can add many Outlets to a Product).

The relationship works well, but I would like to add metadata to the relationship - i.e. information that is specific to that particular Product/Outlet relationship.

I was considering adding a new ProductOutlet custom post type, but I suspect there might be a better way of doing this?