Yahoo email transition- only one address?

I have two Cox emails currently.  I received the notification on my secondary email of the transition- I transitioned that email successfully.

Regrettably this transition is apparently only going to work with one address, not two.  This means that my main email address is going away- the email I use to correspond with family, friends, banks, brokerages, e-receipts, etc.

My understanding was that Yahoo would handle multiple addresses.  Was I hoodwinked into relinquishing the main email address or will that receive its own prompt?

Please be advised that I'm on the verge of an impressive tidal wave of profanity.

Thank you for reading.