I don't think you can. It would defeat the purpose of the Anti-theft. The key needs to be removed from the ingnition in order to lock it. Just like you cant lock the drivers door with the central locking system if the door is open. Unless there is a coding option, I don't think it can be done.

You would have to carry both keys with you if you did get it working.

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2011 E70 50i M Sport