If I replace an existing user's account information with a new user's information, does Cadence retain contacts and messages connected to the account?
If you swap out a user and keep the same User Id, both the previous messages and the previous contacts will remain connected to the user.
If you utilize a new User Id, a team Admin will need to import the contacts with the new User Id in order to connect the contacts, as the previous User Id will no longer exist in Mongoose. After that import takes place, the previous messages will also be connected to your new user.