I have a need for a recursive function and don't know where to start.

 

In the form shown below, I have a sub form for Unit Entry.  I need to create a way so that every time someone enters a line item in the Unit Entry sub form  the system will generate a list of those items with the same unit number, sales order number, and work order number but for each individual part, it will generate a new serial number.  In other words, In the example shown, my user enters quantity 34 of the unit number 1234123.  In the back end there should be a list of 34 "parts" created, each with a unique serial number but the unit number, sales order number nad work order number should match that of the orriginating sales order and each other. I've been troubled wtih this for weeks and am running up on a deadline.  Any help you can provide would be greatly appreciated.  Thank you!