Huk24 – New vehicle, old contract and vice versa

Hello. I couldn’t really find it in the FAQ of the HUK24 right now, but maybe someone already had this situation and can give me a tip. In a few weeks my new car comes and I would like to register it on my current contract. However, the old vehicle should not be logged off for the time being, but instead run as a “second vehicle” on a new contract.