Domestic + international shipping cost consolidated

Hi,

we are running a marketplace with WC Vendors.

We are located in Miami.
The vendors in our marketplace are located across US.

A vendor first need to ship a package from his/her city to our address in Miami.
We`ll then ship the packages to their customers abroad.

I have the table rates for domestic and international shipping (two different shipping companies).

I`m using the WooCommerce Table Rate Shipping plugin from Bolder Elements.

However, I can`t figure it out how to put together domestic + international values from each shipping company and return only a single shipping cost in cart and checkout page.

Can anyone shed a light please?