Hi, we're in the process of setting up our shopify, and we're looking for an app that will allow us to connect our inventory with another shopify store--one that we do not control but their products will be sold through us. Additionally, perhaps related and perhaps not is something that would allow us to send them the invoice/packing slip through shopify. Please let me know if you've any ideas!
It depends what software you are connecting to and what options they have whether API or FTP. We connect different platforms like ERP systems and other systems for our Shopify users so everything can be automated. Our system is actually designed to pull inventory from other systems and map them correctly into Shopify.
If you want to send through more details of the systems you want to integrate we can investigate it for you. My email is email@example.com