The most painful part of the process is moving as an adult.

The HOA said I would be fined if any more complaints are issued.This is obviously an issue for the other tenants, but mine is a man and his adult special needs son.

We have run into this several times and have reached out to the emergency contacts, generally an adult child. 

You can also consider joining the American Apartment Owners Association.

I had to experience the glamour myself.The feds can definitely rope you into trouble over this, some cleancut young agents and an assistant US attorney looking for an opportunity to advance their careers, and you'll have all kinds of fun trying to explain your loopholes and technicalities to a federal grand jury, most of whom will, of course, at least dislike landlords and think their activities should be more carefully regulated, as most non-landlording Americans do.Buy hey, paint that target on your back, go right ahead.

Run separate background/credit/rental history on each, and that comes at a separate cost for each...Remember, one applicant may be glowing, while the other is trouble, so you want to check everyone.Everyone 18 and older is an applicant and will be on the lease, so add any adult kids to that process and collect those fees as well.

Maybe I'm not searching properly but a lot information I see are American and not applicable to my situation unfortunately.

So I would encourage you to talk with your adult family members and find one who wants to create an LLC with you to buy real estate.  

4 Unrelated adults in a single family home. 

In my opinion the ONLY way you do that is by treating him like an adult and simply being up front and honest, and say "I'm not renewing your lease so here is a 30 day notice to vacate".Avoiding difficult situations isn't going to make you or him better off.