I work closely with many buy and hold investors and would be happy to share insights or explore ways we can collaborate. 

I am not suggesting that you cannot diversify however are you looking for cash flow or is buying now, holding for appreciation and or forcing appreciation is your play.Good luck on your journey!

If he is ok with not owning the properties  The easiest thing to do is buy him a house. 

Or generally, for deworsification, just buy into 10?   

It depends on where you want to live, income, personality, and other factors.You could buy a large home and rent out the individual rooms to cover expenses, but this comes with problems.

Are you looking for a house to buy or manage here in Florida, as an airbnb, etc?

However, there are ways to leverage SBA loans so they can buy a new primary and then look at their current property as an investment property and secure a DSCR loan to redevelop and rebuild.

2) Can we not pay anything if buy 2nd home in same LLC?

But it feels like if you keep cashing out equity on your properties to buy another, you end up with multiple properties but with your equity stretched really thin, like a house of cards ready to collapse. 

Also, you don’t need a business license just to look at properties, but if you buy a bigger property, like a multi-family unit, you might need a certificate of occupancy, depending on the local rules.For business trips, most expenses can be deductible, but if it’s part personal and part business, you can only deduct the business portion.