Dividing Address on Property

[Kady Daniels]

Hi There! My husband and I are about to close on our first property. The seller has been working with the city to get a Certificate of Occupancy (was a single home, she divided into two units). I can't seem to get a definite answer from anyone. How would we update the address to add an A/B or unit 1/2 etc. onto the two units now? Is that process included in the CO? or Do we just need to go down to the Post Office? 

Thank you in advance for your help! & let me know if you need more information.