Modify Dialplan to add Variable to Redirect Action

As I don’t have the option to set variables/headers for a redirect action in AMI, I am looking for a workaround.
My receptionist is using flash operator panel.
Upon originating calls I use a variable “__SIPADDHEADER51=Alert-Info:info=alert-autoanswer” for my Yealink phone to auto answer.
Unfortunately I can’t do this with redirect commands, such as when picking up from a queue or from parking lot.
That’s why I thought of modifying dial plan to add auto answer headers for my operator extension when redirect action is performed.
Any idea how I would go about that?

Thank you.