If you put her car on your policy with her as a named driver, as it is her as the main user of that vehicle, that would be 'fronting' and is fraud. If you have a multi car policy through the likes of Admiral, then it is possible, this will reduce her premium, as she is using your no claims, but she is accruing none of her own. Should she have an accident (which she is at a 75% chance of on the first year) then you will lose a percentage of no claims, and this will increase both yours and her premium. Much better for her to start from scratch, start her own no claims, get a telematic box in the vehicle, and buy or lease a relatively new car. All of these things should make the premium more affordable.