Me and my friend, lets say Sarah, made our account at the same place on the same laptop im on right now. We can breed our horses together or send ebs to each other, because I make her art sometimes, But she breeds color and I ratings so if I got a color horses then I would sell t to her, but I can't do that because it says that its both linked back to the same place, therefore we can't do anything with each other.

It's because they were made in the same place on the same laptop. That's why it wont let you because you're not allowed to do thing between "households" Though you arent in the same household, it thinks you are because it was the same place/laptop. Hopefully that helped!