We would like to go ahead and start using serial control for our products.  Using a simple example, I have a  few questions hopefully someone could respond to:
 
We have previously built and shipped five red wagons, serial # 1 thru 5.  We are going to create another work order to build 5 more wagons, serial #’s 6 thru 10, and ship all those through one sales order.  
 
I think I understand how to correctly use serial numbers 6 thru 10  in regard to entering work order finished production and releasing/posting sales order invoices. My concern, in this example, is more with serial #’s 1 thru 5:
 
1)      First, it seems OK that I can go ahead and under the wagon item #, “pre-enter” serial #’s 6-10 thru DBA menu SC-A (or serial #’s up to, let’s say, 100, if I wanted to).  Is this practice indeed OK?
2)      It also appears from looking at SC-A, I can enter serial #’s 1-5 (the five units previously built) and enter the work order #, date received (enter finished production date, I presume) and work order unit cost.  Is this OK too?
3)      If entering serial #’s for  previously built and shipped wagons is OK, how do I tie those first five numbers to the invoice number under which those five shipped?  Searching through the SERIAL and BKARINV files, I don’t see where the serial number ties to the invoice number.
4)      Any general advice/precautions in regard to using serial # control?
 
Thanks!
Mike