Based on what your asking for, I would say Invoice ID should appear on the deliveries table, and delivery id should not appear on the invoices table. The only thing I would question here is it seems like the possibility of human error is high. You should make sure to use some kind of control, like a form control combo box. It may be a good idea to show more than one field in this control as well.
Other things to note: you should avoid using spaces in the names of access objects and field names.
A bigger problem I see is that you have the field customer id in the customer table and invoices table. Make sure this isnt an error! If customerid field is needed with invoice records, use queries to bring this info together.