Can we update the Requested for details on the RITM ticket using the "Requestor:" in the description

We have Integrated Slack with ServiceNow for overtime requests from users where the emails from Slack get forwarded to ServiceNow with Recipients as "callouts@xxxx.com". We have created global Inbound workflow with decision tables so that it creates a RITM once the email is forwarded from slack. But as of now the Requested for details shows as System administrator. The details of the Requestor and overtime details are getting captured in the description of the RITM. The body of the email from callouts@xxxx.com has the Requestor details who have raised overtime requests. We want to copy the same to the Requested for of the RITM ticket.We are unable to update Requested for details on the RITM ticket using the "Requestor" values in email body coming from callouts@xxxx.com. Is it possible to copy the same either from description of ticket or email body which is coming from slack.