I bought the 9 properties within the first 2 years, but haven't bought one since.

There are many people on instagram and other platforms selling courses appearing in a certain image, selling a lifestyle that is not 100% congruent with reality and sometimes reality can strike hard and shatter perceived illusions. 

It is not retaliatory in nature also.Is it legal to raise rents on one property and not all of them?   

., "I will buy at least one single-family home, duplex, triplex, or fourplex before the end of 2019") and then do it.

The need for a home and an office under one roof.

Couple is splitting up and one is wanting to stay. 

The new heat pump all in ones (120 instead of 240 and don’t need venting) are much better than the older all in ones.

Strategy 1: buy a duplex, live in one unit (for one year as a "primary residence) and rent out another unit as a short-term / mid-term rental on Airbnb.

And one side was already leased.

You'll also want to coordinate with your estate plan, and consider getting an estate plan if you do not yet have one in place.As to the trust, that's generally an estate planning tactic rather than asset protection.