My daughter has a 2018 Nissan Juke in very good condition, while my granddaughter has a 2017 MINI - also in very good condition. But she would like a bigger car as she has an 18-month-old baby. They think it's a good idea to exchange cars but although they are both in favour of this, other family members are not so sure. Would they need formal documentation to do this and what potential pitfalls could come into play with this type of exchange? My granddaughter's insurance is due 2 November so probably needs to decide soon as to whether this is a good idea or not. We do realise that both vehicles be appropriately insured. Many thanks.