How to load specific wagons

Hello,
As a relative newcomer (started around the second quarter of last year), I still don't get how to load just some specific wagons of an AI train at an industry. If I have a train with different types of wagons and products they can carry, when I give it the "Load" command, it tries to load all wagons of the consist, not just those that carry the products produced by the industry it's at. That can be painstaking at times.
I looked up in the DLS in scripts and rules and found nothing of the type.

Any clue?

Thanks
TM

The "station" will have product queues which align with the products that can be carried in a wagon. Passengers are a product by the way. Middleton for laptops has different wagons carrying different products that load and unload so that might give you a clue on how it all works.

Cheerio John