You could create a Worksheet of your Customer's information (let's call it Customers) and then have VLOOKUP formulas in your Shipping Document that pull the customer information.
Customer Worksheet:
Code Name Address
PEG Peggy Olson 10 E Madison Ave., Suite 205
DRP Don Draper 10 E Madison Ave., Suite 100
Shipping Details Worksheet
This would have a formula for each column you want to lookup. The formula would be something like:
=VLOOKUP(A2,Customers!A2:C5000,2,FALSE)
This formula says: using the value in A2, look up the table in Customers from A2 to C5000 and return the 2nd column. The FALSE says that the customer code must be an exact match.
Now you should be able to just type the customer code in your document and it will automatically lookup the other values (i.e. Name & Address).
If you do not want to see the "#N/A" for those rows that don't have a customer code (or where one cannot be found) you can update your formula to display a blank when there is an error.
In otherwords:
=IF(ISERROR(VLOOKUP(A2,Customers!A2:C5000,2,FALSE)),"",VLOOKUP(A2,Customers!A2:C5000,2,FALSE))
Hope that helps! Some pictures are attached to showcase what it would look like. The highlighted section is automatically populated.