A motor trader's policy is only for those who operate within the motor trade industry.
Being a broker in the motor trade industry there is probably one question asked more often than any other. That question of course is, "Can I have my brother and wife on a trade policy?" To most people it's not a silly question. But let's lengthen it a little. "Can I have my Aunty on the policy, how's about my nephew? I have family visiting from Italy, can they get on it for the weekend? You know, a kind of reverse EU breakdown recovery?" Yes there are certainly ways your immediate family, such as a Wife can be on a policy but not your entire family tree.
A motor trader's policy is only for those who operate within the motor trade industry. You either need to be selling or buying vehicles, repairing, owning a vehicle or hundreds or operate one. Either transporting goods, offering services from business premises, requiring all road risks or stand alone building insurance with certain cover for indemnity. All of these will have public liability insurance built in. There are two differences however. The policy will cover vehicles you own, and or vehicles you are allowed to drive. Covering either the business and owned vehicles or owned vehicles by a policy holder.
As a secondary notion and one you need to inform the broker and underwriter of at the time, is how many named drivers you have. Your brother can drive a vehicle and be covered if he is an employee or named driver - but additional drivers may push the cost of the premiums upwards. Your wife can be accepted onto the policy if Social, Domestic and Pleasure use is enacted Can I have my brother and wife on a trade policy?. No. Nor his Wife!