In our county the occupying parties do not have to be related.
For the new construction: In my case I have to buy a separate sewer line (which is not metered - just flat fee). I may use the same water line if I wish. I will split the gas and electric onto its own meters.
For the existing home: I have to install a separate heater that is thermostatically controlled from inside the apartment - I found a nifty little unit that will do the trick for under $300. I have to make sure that the breakers are accessible to both units 24/7 (they are now on the outside of the house; so no problem there). I had to pay an extra fee for the potential additional sewer usage - but did not have to install a separate line. The water, gas and electric are all on one bill - so it will have to be a "utilities included" rental.
As far as addresses - you can request that an address be assigned. But in my case the lots on either side of me are already 488 and 492. I am 490 - so I will have 490 A,B,C & D - with four mailboxes curbside.