Okay, then how it will be linked to specific Help Topic as I need this field to be dynamic based on Help Topic selection. Is there any way where I can use this in Ticket details form where list will be changed as per help topic selection?
We do not have a "dependent fields" feature at this time so you cannot have a field that depends on another field to populate data. There is no way to accomplish this at this time unless you modify the code. You can however have fields appear when choosing certain Help Topics but that about it.
One more thing as we have given option QUEUE display of this field than it can be done in Export also as both are one or same thing, see if I can get some clue to change in core files at my end for this
Unfortunately, the Export fields selection is basic for now as it only includes Ticket Details form fields. We plan to add all fields including custom fields to exports in the future so please stay tuned.
Cheers.