To me it makes no sense that I can't level up my companions that are leading other parties or caravans. In my current game I have a companion leading a party that I have following me around in my army to buff my leadership and increase my party size. The only way I know of to level this companion up is to disband his party, take him back into mine, level him, and then reform the party. Not only is it a total pain in the butt, but it is counterproductive. The end result is that these characters don't get upgraded. Taleworlds, please allow us to upgrade these characters without taking them into our party.