Inspections are as individual as the persons who do them. I have encountered within one inspection department interpretations of the code that differ 180 degrees.
In one such large department, one inspector refused to recognize Article 110.26(A) (Exception No.1) while another inspector agrees that it means just what it says.
Your best bet is to just have your electrician apply for a "service change" -- nothing more. The outcome is uncertain.

Are you seriously wanting to hide the fact that you are converting a garage to an apartment???
Don't live people live in apartments? Wouldn't you want that fact known if there is ever a problem? Who do you think will be on the hook if there is?

Petey_racer, it is a garage conversion built to the highest standards. They are known about.

Except the part about 20 amps going there.

They darn well will have a problem, both most likely with the zoning and habitability as well as the completely illegal, unsafe, and undersized service of the separate dwelling unit.

Further you liability is EXTREMELY high with your illegal and unsafe wiring in that unit.

If it's done ''to the highest standards''then why wasn't a permit pulled? Don't worry, our eighbors will likely turn you in before you burn down the house.