Hyde here from Shopify. Great question!
At the moment the only way locations can split order fulfillment is if there aren't enough products in Location A so it automatically draws the remainder from Location B. So if the product cannot be found at Location A it will draw from B.
You will need to set the priority of locations for fulfilling orders to your different locations manually as per this help document.
I hope this helps, give it a go and let me know if you have any other questions!
All the best, Hyde.
If you want to split orders based on locations, it's better to keep multiple stores to serve each domains. For example, example shop.com for US and example shop.ca for CA, and then direct your visitors. In this way, you customers can place orders accordingly from your relevant locations. Moreover, you could control stock, price, and shipping costs flexible.
Hope it helps. Feel free to reach out if you have any questions.
I actually do this right now where the products that are not in location A does fulfill from location B, however, when the order comes in (as it's integrated with our 3PL from shopify), all the locations come in to location A and they can't fulfill all. How can I show where location A's (3PL location), is only seeing location A's products only?