We have 4 relatives that do not have US visas but want to come to visit for a tour of our western states and see the sites. I was going to write a letter to the consulate as I have for our parents to explain the trip but was wondering if I should list all 4 relatives in one letter or is it better to write a letter for each relative? If one wouldn't get the visa the others probably wouldn't make the trip as it's a father, mother, daughter and the father's mother. They would then accompany our parents as they're 87 and 78 years old and unable to make the trip on their own.
They own a number of homes, have good jobs and all their family and friends of course are in China so no 'threat' of them staying in the USA.
Any suggestions and what are their chances of being approved for all of them to get their visas.