Yikes!
Most companies will cover you automatically without rating and charging you while you have a permit only. Once you are licensed, you should be added. Multiples make it difficult, because it is more expensive. but license means needing to be added to policy or excluded from policy (the latter bars you from having any coverage if you drive and means you intend NEVER to drive).
Probably the wisest thing is to set up a separate policy for the three of you and your older car.
Check with an independent agent for help. There are companies out there that right policies of this kind for teenagers.
Good luck!

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