Adding a Miscellaneous Item
Head to More → Settings → Advanced → Miscellaneous Items
Select +Add new item
Complete the relevant details to create a new miscellaneous item
You can now add the Miscellaneous item to any new/draft invoice or credit note:
Editing a Miscellaneous Item
You can edit a pre-existing miscellaneous item by selecting the action cog → Edit:
Archiving a Miscellaneous Item
You can archive a miscellaneous by ticking the line item and selecting archive: