Transitioning to Yahoo Mail with an Existing & Matching @comcast.net Yahoo account

Hi. I just found out that all @Comcast.net emails are transitioning to Yahoo Mail. I haven’t received my email invitation yet but I have an existing Yahoo account with a username of *****@comcast.net that matches my username for my Comcast email. How will the transition work for me if they are the same exact username but obviously different passwords? I might be a minority here in this. Just wondering if there’s something I can do to make sure the migration works correctly. I’ve had issues with my Comcast email for years saying the inbox is full (storage) and I won’t receive new mail. A lot of emails never arrive in my inbox so I’m eager to get the migration completed to avoid this problem.