Establish a legal structure similar to European systems. Clerics are employed to record all land grants or financial affairs. Charters are legally binding documents. If they are broken, punishment would be justified.
You're being a little rash. It would be unwise to use force on such powerful and wealthy families. They are much better as allies than enemies.
Establish a land-holding relationship, wherein you grant money as a reward to the lords in exchange for their support and loyalty.
Which card will you play?
