title: Best way to link a user to their data in Firebase?
body: <p>I'm using Firebase for authentication and Cloud Firestore as a Database in my app. To link a user to their data a created a Users collection and each document name is a UserId that I get from Firebase Auth. My problem is if a user creates an account using email and password but then signs in using the same email but with Google Authentication instead, the Google Auth overwrites the Email and Password Authentication and the UserId changes.</p>