I think you have to add the custom segment to the header (to get it on shipping). You should be able to have it on both sublists - you likely need to customize your form.

Hey Kevin, I am attempting to pull the custom segment from the item so I see a problem with putting it on the header. Is there an easy solution that I am missing? There are times when the header doesn't necessarily work because there can be two different values for the custom segment depending on the line item of the transaction.

You'll just have to deal with that.

Thank you! I am thinking of leaving it blank and month end doing a journal to assign it to the two separate custom segments. I don't see a productive way around it

Sounds about right.