Common Shipping Method

After almost 10 years using CS-Cart, this is my first time on Multi-Vendor setup.

Explanation of problem:

When a vistor adds to his cart 2 products from 2 diferent vendors, in checkoout, there are 2 different Shipping methods. In my case, all vendors have a shared Shipping method from 1 common warehouse.

I'm looking for answer to this:how can I combine all Vendors' Shipping methods to 1 general?

FireShot Capture 419 - Checkout -

There is no easy way to do it out of the box. Additional code modifications are required

I have the same issue. How did you resolve this?