Hosting tournaments, feasts, sending gifts, more town projects
A possible solution would be to make high tier troops available from a new 'constable' notable located in castles for a premium. Currently it costs 350 to recruit a vlandian knight from a backwater village which is laughably small, making the noble line troops much more expensive and available from castles only could be a solution
All for those too. I bought Viking Conquest and Napoleonic wars and would gladly pay for a similiar module dlc system