Item hierarchy in sales order

Hello,

I have a question regarding Item numbers in sales order.

I have created a new sales order type, and my requirement is to have a three-level hierarch in my sales order.

Exemple:

Item number High Level Item Material 10 0 Material 1 1000 10 Material 1 -1 1010 1000 Material 1 -1 -1 1020 1000 Material 1 -1 -2 1030 1000 Material 1 -1 -3 1040 1000 Material 1 -1 -4 1050 1000 Material 1 -1 -5

In the customizing of my new document type, I found the options Item "no.increment" and "Sub-item increment", but I don't get the result I'm expecting.

It works for 2 level hierarchy only.

Can you please suggest a solution to achieve this?

Best regards;