In the early chapters of the game, you can hire a generic Nurse unit. There is a well-known exploit involving the Nurse's healing interactions.

Berwick Saga has a "reqruitment" system similar to Fire Emblem: Thracia 776 . Some units will not join you unless you meet very specific criteria.

Disclaimer: Cheat codes can corrupt save data. Always back up your memory card data (or PCSX2 memory card file) before activating codes.

While I can't provide specific cheat codes without more details on the Berwick Saga game you're playing, I hope these tips help you find what you're looking for. Always use cheats judiciously to ensure they enhance your gaming experience rather than detract from it.