We are renting from him for $100/month while we finish probate.

I can't speak to that since it's all irrelevant on the master lease - we get our agreed-upon rent on the 1st each month and that's that.

Renting in NYC adds risk. 

And IMHO, the prices are dropping big time (on avg. 10K/month...houses that were above 300K a year ago are not selling at 250K now) and the available rentals saturation is worse than I seen during summer season (with rents dropping from 1$-1.08/sqft to 0.8$/sqft and very little contacts and applications...just go in Zillow and look how many rentals are on the market now in Kyle, New Braunfels or Converse). 

Both "2 bedroom" units were listed as having the same market rents. 

@Aubrey Eblin Thank you very much for sharing your experience with the Rent To Retirement Academy. 

Living in top unit and renting out the bottom.

My primary residence is an apartment I rent in Brooklyn NY.

You can also go on zillow/FB marketplace to see what other similar properties are renting for around where your place is at. 

I enjoy tenants turnover ever few years for the reason fair market rents tend to increase significantly year over year.