Not sure how applicable this is, since it is (1)a different jurisdiction (2)a house built in '48 with a 1-bed apartment with kitchen & bath added in 86; but my

Not sure how applicable this is, since it is (1)a different jurisdiction (2)a house built in '48 with a 1-bed apartment with kitchen & bath added in 86; but my brother's house has the apartment separate from the main house with a connecting HVAC/laundry room. As many apartment buildings also have shared laundry, perhaps investigate that route. Sharing laundry with a tenant isn't much of a bother, and in my brother's house the apartment was quite literally built for the mother-in-law. There is still separate HVAC, but in this case all that is needed is an adjoining laundry room w/ 2 fire rated doors.