[dev] Add TicketKey and Value in Postmaster/FollowUp?

Hello, We are investigating in an mechanismen to couple HP ServiceDesk and OTRS. One problem is the ticket reference on both sides. We agreed to keep each others ticket id and do update. We used the ticketkey and ticketvalue free fields for this. Unfortunately an update of ticket free fields is not included in FollowUp. Is there a possibility to implement this in the FollowUp.pm or any other ideas? Regards Thomas Kaiser