How do we update OnHand and OnOrder values when linked to Shopify

Shopify does not allow us to send purchase orders that we generate in StockTrim through to them as a complete purchase order.  We can update the skus in Shopify with the updated amounts we need to order individually.

The process is as follows:

1. Generate a po in StockTrim, download it as a csv or pdf file. Put it into your own format as required and then send off to your supplier via email,
2. When the order arrives log back into StockTrim and then you receive this purchase order in the Manage Purchases section, and the onhand and onorder amounts will update
3. Our updated on hand amount will sync back and update Shopify
4. Then Shopify will return to StockTrim the current onhand value at the next sync