Clerk Metadata data loss if user signs in using the sign up modal

Hello, first time working with Clerk. this is my auth flow: I ask user for information about the new project they're trying to start. I write this information in my database. User is asked to finish the sign up flow using the clerk's Sign Up modal.
Clerk supports adding metadata to the user object during the sign up process, but turns out, if the user already has an account and uses one of the SSO providers or sing in button, they'll get logged in into their existing account and I'm losing the metadata & therefore I'm unable to link the project they started to their account ID. Any ideas?