We are looking for an app which will allow us to bundle a number of items under one product which cannot be edited within the cart. When the customer checks out with their bundle I need the products to still be able to be fulfilled separately in the backend of shopify, in cases where 1 of the 5 products are backordered and needs to be shipped separately. For example. Customer buys product A which includes product B1, B2, C1, C2, C3 but C3 is delayed a week and needs to be shipped separately. So I can ship out products B1, B2, C1, C2, with standard shipping operation in Shopify, then C3 stays unfulfilled until the stock arrives then I can ship C3 out to the customer separate and finish fulfilling the order.
We have built a new app for this scenario. The way it works is basically how you describe in that you build the bundle from existing SKUs and we push it into your Shopify store as a unique product. You can also have variants on it set as different bundles. When an order comes in for this product we convert the order into the individual components so you can fulfill correctly the actual items. It also lets you manage your inventory correctly.
You can then manage your orderlines as you mentioned individually so the order is partially fulfilled until all lines are shipped. We also have our own UI where you can view these orders and build automations around how they are processed when stock is received.
If you would like to test out the function just send me an email to email@example.com