Can you refuse to add someone on the lease just because they are disruptive?

Can you refuse to add someone on the lease just because they are disruptive?

You have to treat every equally.

The person that is on the lease is responsible for the behavior of their household and guest , that who I be communicating with

Sadly but also not sadly - we have fair housing for this reason.
Otherwise I’d have turned away lots of applicants over time.
If they are being a disruptive guest though, then you should have been issuing lease violation notices to the resident. You’d need some sort of paper trail.
But I’d consult with your attorneys first as well. I’ve never had to ban a guest from the property before. Let alone one who’s potentially going to be a future resident.
If you do add them to the existing lease though, you could always non-renew them?

YES.

Depends on what you consider disruptive. But, Yes. You treat it the same as if you received a rental reference stating that they were disruptive. Only, this time you witnessed it first hand.

Our application has a section saying roughly that this is a business relationship and if we feel we will not have a positive business relationship with you we can deny the application. It's wordier, but if they are raising flags during the showing or application process (disrespectful, yelling, swearing, threats, etc) and we know this won't go well we can end it before it starts. And obviously, document well why you are denying for such.