On that, along with contacts tags
I had something implemented a while ago, as important/primary contact that could be labeled (owner, billing, ceo etc). problem was that only one important/primary contact is allowed to have for the moment.
this would also help to outline the contact as approver or need approval in the ticketing.
IT glue, lets you set as many contacts as you want as primary/approval
like this, integration ITGlue with OSTicketing
https://ibb.co/2Fx2sQZ
https://ibb.co/sWKyjMm
https://ibb.co/Ht2CYkV