I'm considering selling a single-family house we've own and rented for almost 5 years. 

As I continue to grow my portfolio I’d like to continue with the because their interest rates have been the best I’ve seen and they keep their loans in house.

Housing stock is much older.

I am planning on house hacking another multifamily putting only 3-5% down in a year.

Cousin A currently lives in one half of their primary residence and rents out the other half.Cousin B has a rental property they want to get rid of by doing a 1031 exchange.If Cousin B buys 50% of Cousin A's house as tenants in common, can A & B essentially switch over the rental income to B, whereby B reports all rental income and expenses on their taxes and A reports no rental income and expenses?

I've done similar things with adding or remodeling while house hacking and needing funding to do so.

Before the work, our house elevation was +0.5  readings the highest,  - 2.5  in several other low spots. 

After expenses, it will be cash flowing 1k/month.My thought of doing a 1031 exchange seems like an option..trade in a 170k house for a few 250k homes and increase my portfolio by 600k.

Sell as a seller finance with 10% down and charge about 8% interest increasing the monthly income. 2.

I've recently came across this technique of assuming the sellers mortgage when purchasing the house.