Converting SFH into Duplex

[Patrick Fanning]

I am looking at a SFH 5bd/2ba that has an in-law apartment attached. That apartment has its own bathroom and small kitchen with separate entrance, which would be ideal to rent it out separately. My question is, since it's zoned as residential (R-1), is there anyway to get this rezoned for a duplex. Are there any ramifications for renting it out as separate units as a SF?