Thank you!
To gain the favor of each knight you have to repair their weapon correctly and also choose the right dialog choices afterwards. Theoretically (if I did my job right) choosing certain dialog paths in the other two knights' dialog should give you clues on what the correct choices are. I believe Lady Odette gives you a clue on how to repair Isabella's staff, and Lady Von Sunflower gives you a clue on what to say.
Also the way the logic is written, I'm pretty sure you have to intentionally do the wrong thing for both Odette and Von Sunflower.