My question involves landlord-tenant law in the State of: Washington
I leave in a house with 2 units. I share the yard and the basement with neighbors (all tenants) upstairs. We are 5 people: me and my girlfriend living downstairs and 3 neighbours living in the upper unit. We don't have any specific bylaws.
Me and my partner had an argument with a friend of the neighbors. He even threatened to sue us (I have that written in a private message). The relationship with the neighbors remains OK and they understand this conflict was not with them, but when they do parties in the garden they invite this person. For obvious reasons (he has been openly hostile to us) I don't want that person to be in a property I share.
Questions:
1) Can I just ban a guest from a property I share as a tenant?
2) Can I do that based on written conflicts? I have the proof of that hostility.
3) If invited and finally joined that party, can I engage him in an uncomfortable conversation saying he has to leave or even call the police denouncing unwanted guests?

