-Grant H.Photo showing small gap between dwellingsPhoto showing the "connector" inside this small gap between the dwellingsBlue outline: Townhomes/condo style dwellings.Orange outline: Completely separate single-family dwellingsRed outline: Two properties pictured in the first photo above

Can anyone suggest a book or website where I can learn more about this topic?

Fill in the foundation below.Check out the Start Here page http://www.biggerpockets.com/starthere Check out BiggerPockets Ultimate Beginner's Guide - A fantastic free book that walks through many of the key topics of real estate investing.Check out the free BiggerPockets Podcast - A weekly podcast with interviews and a ton of great advice.

Dig in on this topic!  

I will look into the reference you've provided as this may shed some light on the topic.

Here are some recommendations for you:Find and connect with other BP members that are in your area: http://www.biggerpockets.com/meetSet up keyword alerts to be notified of the topics that interest you: http://www.biggerpockets.com/alertsRead Beginner’s Guide: http://www.biggerpockets.com/real-estate-investingCheck out BP Podcasts: http://www.biggerpockets.com/renewsblog/category/podcast/If you wish to tag someone in the conversation on the forum, type @ followed by their name and then select the name of that person which should appear below the comments box.

I then got into the topic of real estate.. 

Whether they keep is tidy is another topic!

Thinking about your situation, you might want to read my last comment in this thread (https://www.biggerpockets.com/forums/12/topics/284...) not to sound my horn, but I think what I wrote there might help you also.~ James

Having something in writing is always a good idea, especially outlining what is and isn't shared (e.g. common space, garage, outdoor space) with others.