Insurance after divorce

Hello, the following: my parents divorced about 3 years ago. I would like to buy a 325er and of course it should be insured as cheaply as possible. before it looked like we had two cars, insured with the hdi (insurance taker my father). Both were in the same SFK 9, i.e. 45% although we had drivers under 20 years (me). Now I wanted to ask myself if it is possible if my mother would sign a new contract for the 325er. 5% can take over and then register me as a second driver.