My wife's Siter and brother-in-law expressed their interest in visiting USA. What Visa type they have to apply? My wife and me are here from last 10+ years and we are GC holders. Can we apply for their visa like what we did for both of our parents or have to apply on their own. What are the chances of getting visa approved for tourism purpose and how long it will be allowed to stay and how many years the visa is valid?

Thanks in advance to forum. Please share your visa interview experiences as well if anyone has applied for this type of visa before.