We don't currently have an option like that. The "join string" comes directly from MusicBrainz, and it's usually something like "and" or "feat.".
However, this is a fortuitous time to be asking about this. Recently, the MB style guide changed to allow a broader variety of join strings, so the "client side" has been asked to provide ways to normalize this for users. Here's the discussion regarding Picard:
Maybe we need a ticket of our own to request the ability to customize these? Perhaps with a dedicated config option (or set of options) to the MB data source?