Visitor visa extension question

[paachoo]

My father and grand-mother are here for the last 5 months in US. I am in the process of applying for an extension on medical grounds for my grandmother. Two questions:

1. What is advisable, use my father as the main applicant or my grandmother
2. Since I am using the same application form for both of them, I am assuming it is a $300 application fee and not $600, right?

Thanks for any advice.

-p

[immihelp]

2. You will have to do that separately for each person. Father and grand-mother can not be considered the part of the same family.
You will have to pay separately, therefore.

1. Not applicable based on answer #2.