Changing a single family into multi family

[Brittany Fife]

I have a four bedroom single family with an attached barn. I was thinking about making it into a multi family. A three bed one bath, upstairs, one bed one bath, downstairs and a 2-3bed one bath, barn. How do I go about changing the address? Do I need to get permission from the town? Do I have to petition it at the town meeting? Does anyone have personal experience doing this before?