As I understand, you would like to have new fields, having the same choices as for an Incident?
Some food for thought first. A KB Article can potentially be linked to multiple Incidents/Incident types. Have you considered that? If you add dropdowns, you can only select 1 cat/subcat. Agents would need to set those manually. Is it really needed htough, with the search/AI capabilities of SN articles can rather well be linked to related Incidents anyway.
That being said, you can add two new fields to kb_knowledge table, those would be choice fields, and in the settings you can say the choices should be taken from the original Incident field. That way, if Incident choices change, in KB this would be reflected automatically.
