How to update new stock supply in QuickBooks and POS systems?

[BCS2020]

Dear Community Experts, I have set up a retail store, which has shopify POS and quickbooks online. When we first opened the store all products procured manually and the same was created on shopify first. When quickbooks was integrated, the same products where created on quickbooks. This is perfectly ok first time. Now comes the dilemma, since some of the stocks went zero and new products came to market we have placed the order to a supplier. Supplier has sent us the invoice, where should the new order details be created, shopify or quickbooks? or rather what is the procedure or method which can become a standard. Is there a clear steps for updating the new supply? May be I am ignorant about this, but these things if both shopify or quickbooks can come up with a simple solution then it make life simple for retail outlets. Hence I would like to ask community if one document about this is created it would be a great help. Thanks, BCS2020