In the UK almost always the person’s name.

The day of the wedding, I jokingly referred to my brother-in-law as "brother-in-law" once or twice because it was a brand new thing. But ever since, it's "Lee."

Try something and see how it goes. If I call my step-sister "Sis", she acts as if she's going to hit me. Not the same, but maybe a lesson there, anyway. . As Lorena says, in Western society, we often just skip all that. Try "Hi". Using names, virtually every sentence seems to be a British thing. Sounds creepy or British when you hear it here.

It's sister-in-law or brother-in-law. We only use these terms when talk about the person to another person. So we would just address the 'sister-in-law' by their name. Or if you're really close you can just call her your sister;)

Aside from your parents, it's not really common to address someone by their relationship to you in English. I live in North America, and half of my family comes from Mexico so from my experience I would say in Spanish it is common to address a sister-in-law as a sister-in-law. But in English, it's seldom. The interesting part is, in English it would come off as rather 'cold' to call someone by their title, whereas in Spanish it creates a bond.