UPS Shipping, Tie Warehouse to Manufacture

Our products are manufactured and shipped from 3 separate locations (identified as warehouse in the UPS Shipping module). Can anyone provide advice on how I can link each warehouse to a specific product based on the manufacture identified in the product setup. Each of the 3 locations manufacture specific products and none of the locations has the same items. The challenge is to configure UPS shipping module to properly estimate shipping based on where the items will be shipped from. It looks like UPS uses the available warehouse(s) and figures out which one is the most cost effective location to ship from. I have identified each product with a manufacture but the UPS module only identifies the warehouse. Thanks for any advice. Dan

That's indeed the case. the warehouse system of the UPS plugin will use the warehouse "closest" to the customer.
If you want it to not do like that but instead choose the warehouse based on the manufacturer of the products in the cart, you will have to change the code of the function _getBestMethods in the file plugins/hikashopshipping/ups.php

Nicolas, Thank you for your quick response, I really appreciate it. I'll give that a try.