You need to check your state laws and your lease.

Best part is NJ is not what its made out to be in terms of landlord friendly, the state gets portrayed as the entire state being bad when really most wacky laws are in the major cities and they apply to 5 units or more.  2-4 unit multi families fly below radar per say. 

Its hotel law not landlord law. 

My family is in SoCal and my in-laws are in KC.

Are there some local laws I am unaware of or why is this happening?

In Oregon you can kick out who ever is living there unless the federal law regarding arms length leases comes to play..

Preliminary experience stemming from construction as a young adult to gaining my degree in law.

My Brother in law has a company that does this and hand full of realtors have him on speed dial 90% is pipe burst done in a few hours 7 to 8k per..

My plan would then be to diversify by partnering with my mother-in-law on fix-and-flip projects for a year or two, which would increase liquidity.

Invited one of the neighbors over, with his visiting father in law.