Moving flights from EDDT to EDDB

I've converted Berlin Schoenfeld to Berlin Brandenburg (EDDB) with ADE, and now ready to disable Berlin Tegel (EDDT) all together.

My question is how to move all Tegel flights (WOAI) over to Brandenburg. My first thought was to delete Tegel, move the EDDT ICAO code to Brandenburg and re-assign EDDB with EDDT, but I don't want to lose the correct code for Brandenburg, so I'm open to any suggestions or ideas on how I can make a clean switch of EDDT flights over to EDDB without changing the proper ICAO code @ Brandenburg.

Thank you.