Linking multiple auth providers with Firebase on Login

Question

I wish to link multiple auth providers on the time of user signin into the app . Firebase docs provides a method to link a new auth provider with logged in one but I wish to

Answer 1

Linking accounts requires that the user authenticates with each of those accounts.

By signing in to an account/provider, the user proves they "own" that account at that provider. There is no way to link accounts without requiring the user to sign in to each account.