My partner is American (we live in California) and wants our child to learn violin. I want her to learn fiddle.

What instrument would she like to learn? Her wishes in this matter did not seem to me to have been articulated in your original post.

Are you sure it is her that would like to learn fiddle/violin and not you and your partner? It is vital you are clear what she would like to learn. It may not be easy, but there is a rather good book called "The right instrument for your child" or something like that which looks at choice of instrument from all angles both musical and non musical.