Hi Manish,One good place to befriend and spend some time is in the city planner's office. 

@George Wines, I'll chime in here, but @Mike Wood and NA Beard are right on.As a former city planner in the Front Range, I can think of several legal issues preventing you from condominiumizing a duplex.  

I'm currently Planner with a county agency and working on an MS in Real Estate and Infrastructure (which is more focused on commercial RE), but have been planning to get into REI as a part-time business for several months.This family member wants me to work on getting a real estate license first to learn the ins and outs of the business and setting up deals, as he has.

I have a planner that I write everything I need to do for the next day and at approximately what time I plan to do it (some times the kids like to make that a challenge).

I'm currently a financial planner for a living.We have a long history of real estate in my family, and it's an area of passion for me. 

You might go visit the city planner.  

I am a retired financial planner and have helped many clients navigate the system successfully.

The planners, if they are doing their job, should be addressing blighted areas, identifying them and seeking solutions.You'll find that this area of RE takes in all kinds of social aspects along with physical building issues.

Since your parents are involved you might want to speak with an estate planner and drop the home into a family trust with you as a beneficiary or executor depending on your plans and theirs.

Hiring a firm that has a good relationship with the town planners will smooth the process.