You just need to be clear about the scope, and whether or not someone is “in charge”. I had a pseudo symbiotic relationship with the choir director in one post, but eventually she was picking the music and my requests were usually vetoed and it was awkward on a few occasions. It was never really clear who was in charge, because I played three masses, and she only directed at one, but it seemed like she got to make the final call on things.

So, you’ll need to know: is there a shared vision for the various liturgies (ie, will the be the same-ish with simply someone different playing? Or will you each “do your own thing”?) and what the expectations will be schedule-wise. Do you always take the same mass? Or will you be expected to be flexible and shift week to week, etc.