How to predefine shipment set values

Summary:

Our quote and order entry system is CPQ. When the orders are imported into FOM, we need to find a way to group order lines into a specific shipment set name. For example, if the order has 8 lines, the first two lines of the orders should be tagged to shipment set "1", the next three lines should be tagged to shipment set "2" and remaining to "3".

I understand shipment set is a free text, however, our need is to predefine shipment set values in the system, so that we make use of these values while importing orders into FOM.

I came across this old post which talks about a similar requirement, but I am