Create an Opentaps system with some customization work needed

Need to develop an opentaps system the performs that following functions - 1. Catalog management - Be able to create product catalogs by collecting products from different sources. It should be possible to create catalogs organized by clients. Catalogs need to be organized by categories and subcategories and pricing for the same item can be different for different clients 2. Inventory Management - Create a distributed inventory management model which allows a remote user to update the available inventory through a web login / mobile app (can be in future) for products that they are responsible for. 3. Purchase Order Management - Be able to receive purchase orders from clients (or recreate client POs into the system). Based on the various users that may actually be responsible for various items in the purchase orders create back to back POs per such Users. 4. Be able to track the fulfillment level at the user PO level and at the client PO level 5. Be able to receive items and create invoices for clients based on match between the quantities ordered and received Further details can be shared once the freelancer is chosen.