22-year-old (& 18 yo) -- car ownership/insurance

Our 22-year-old daughter is now exclusively driving a car that is owned by my husband and insured along with our other car on our policy.  She technically lives with us, but is mostly at her boyfriend's house during Covid times.  We are wondering if it is time to put the car in her name and have her get own insurance, or can we keep her on our insurance so that is cheaper?   Our 18-year-old daughter is living at home with us on a gap year and rarely drives, but will likely drive more once pandemic lifts.  What is best way to handle insurance?