"Relate to" Field while adding a drug

Dear All,

For the past few days I’ve been struggling to understand the use of this field, I’ve tried everything that I can think of, but nothing has worked.

My understanding is whenever I relate a drug with a code and add that code in fee sheet upon the end of the encounter, then the related drug should also show up in fee sheet, right? I tried these steps but nothing is showing up in fee sheet except the code itself without the related drug.
I even tried the other way around by dispensing a drug that has a related code, but also that didn’t show anything up in the fee sheet.

So could you please help understand what’s the use of the “Relate to” field and how to use it?

Thank you