Where a licensee aggregates a client order, with a transaction for own account and the aggregated order is partially executed, the licensee must allocate the related trades to the client in priority to itself, except where the licensee is able to demonstrate on reasonable grounds that without the combination it would not have been able to carry out the order on such advantageous terms, or at all, it may allocate the transaction for own account proportionally, in accordance with its order allocation policy.