Packing Slips Receive Items

Hi, my brain is struggling, please help.  We create a sales order for a customer, then purchase order to a supplier for that customer.  Goods arrive from supplier, we then "receive items"; we write the invoice number for customer in the "journal memo" for our reference, so we know what invoice or customer these goods relate to.  We then use the invoice number from the "journal memo", to find the customers (sales order) and print the "packing slip" to go with the goods that are sent.  What can I do, if the supplier has a backorder, say we order 2 items and only 1 arrive and I want to then send that to the customer with a packing slip, but the packing slip does not allow me to backorder the item that hasn't arrived? 

Also is there a way to run a report of received items for a day, so we can quickly print all require packing slips.  We basically buy and then sell from many different suppliers to many different customers and many different items.

We have an offsite warehouse and want to streamline their receipting and packing slip process, is there any way to do this better.  

1 Customer orders (Enter sales)

2 Create PO

3 note relating Sales order number in Journal Memo of PO

4 email PO to supplier

5 Goods arrive a few days later

6 Receive items on purchase order

7 Use Journal Memo note to find the relating sales order to print Packing slip

8 If there is a backorder, can't use packing slip, have to turn sales order into an invoice and backorder items then use the invoice as a packing slip

9 if no backorders, print packing slip to go with goods in box

10 3rd party warehouse scans all packing slips at the end of the day and emails to me so I can then invoice the customer

Tell me there are some easier steps than what I am doing.

Thank you