There are companies that will give discounts if you have multiple family members on the same insurance policy. This can be a good or bad thing and can be worth checking out.
Often couples will have a joint car insurance policy, especially if they both drive the same vehicle. This can help to save money and sometimes the value of the policy does not change if an extra person is added on. This is usually the case if that person has no history of accidents or insurance claims.
It is possible to even add children on to your car insurance. This is bound to make it more expensive as young drivers are a big risk. However, it could be cheaper to do this than for them to have their own individual policies.
So the price can be a big factor in deciding whether to have single or joint car insurance cover, but you do need to be wary. If one of the parties has an accident and makes a claim, then this will make the insurance more expensive for everyone. It may even mean that if one of the parties moves to a single insurance it could affect their no claims bonus, even if it was not them who had the accident.
No claims could also be an issue if only the main driver gets to build up theirs. The additional drivers may not be able to build up their own individual no claims bonus and so they may have to start fresh when they get their own individual policies.
If the family has several cars, then it may have different effects than if they are all driving the same vehicle and so it is worth considering this. You will need a policy for each car but deciding whether to have all family members insured for each car or just for one car can be tricky. They may be able to drive any car with their cover anyway, it just depends on the terms.
It can be quite a complicated matter and it is worth looking in to all the advantages and disadvantages before you make a decision. All involved parties should be involved in the decision and made aware of the consequences of this type of policy compared to a single one. It may save a lot of money, but could complicate matters if a claim is made or when a person wants to have their own single policy with regards to a no claims bonus.