If separate entrances, let them do it.

Entrance and exit strategy numbers:1 - cost to get into a market (for sale listings)2 - Cost to get out fast (Sold comps)3 - Cost to get out s..l...o...w....

Is there a separate entrance?

@Joe Splitrock I spoke with my insurance agent and they said they have a product that will cover it as long as there are separate outside entrances.

What are your thoughts on buying a single-family residence with a mother-in-law entrance, and renting out the basement?

A) - Analyze your Current Entrance/Opportunity Cost   1 - Establish property sq ftg ranges, with each range no more than 300 sq ft in width.   2 - List the current properties for sale, and slot them in the ranges (see #1)   3 - Establish what the current entrance cost is per range. 

@Irfan RazaSeparate meter for common areas required only if it's 3-units and more and if you actually have common area (shared entrance).

Our desire is to build up the cash for a down payment rather than take out a home equity loan for our first entrance into this space. 

So Madrid is banning Airbnb apartments that don't have private entrances.  

Access to the MLS and entrance to listed homes at my leisure is certainly appealing.