Changing DoL Retainers Class

Hello there o/

I want to change one of my retainers classes. I want to change miner to fisherman.
However, I dont know if it is possible to do that without losing out on all of my miners experience. Is there a way to change the class without reseting the level, and if yes, how do i do that?

thanks in advance

You lose the exp, it starts over from 0.

It's one of the most painful experiences in the game.

I've done it once now, and I hope to never do it again.