Basically at 20 years, investors would have 16 properties in RE portfolio, with approximately $14 - $24 Million in the account. 

You will likely have cracked drywall and porches will have to be re-installed.

A good agent, who understands RE investing (and actually owns their own) is a great place to start

Do I need to RE- invest $750k in worth of real estate) or just the $400k of proceeds in real estate?  

There is never an agenda, just a bunch of RE junkies drinking coffee and chatting about the market, local news/regulations, and helping each other find their way in the vast world of Real Estate! 

My point is: the question is about open vs concealed vs no carry for a RE business.

I'm not using an agent.I want to allow enough time for myself to find a buyer to re-assign the contract to but at the same time, don't want to drag it out to the point where the seller gets annoyed or doesn't want to sign.

Here is a list of what adding ADUs in my CA market is typically a poor RE investment:1) The value added by the ADU addition is often significantly less than the cost of adding the ADU.

There are, but RE is a business.

I have 17 years of corporate RE and compliance experience, so the LIHTC reporting and annual financial audit does not scare me.