B2 visa grandmother+parents interview

I am planning to applying for visitor visa for my parents and grandmother. I am on H4 and my husband is on H1B. My parents are in their 60s and will have to attend the interview; however, my grandmother is 84 and I believe she qualifies for visa waiver. I understand that I should schedule an appointment for my parents together. Can I include my grandmother’s appointment along with my parents’ application or should hers be submitted separately? If together, would I able to select visa waiver for her later in the application process? Any help/suggestions would be greatly appreciated.

A group has to appear together and at same time for interview.

If your grandmother is eligible for visa interview waiver, then she does not need to be scheduled for interview at all.

The visa interview booking system will not let you add grandmother to the same application if parents need to attend interview while grandmother does not need it.

Thank you very much for the reply. I will schedule my parents’ interview together and submit my grandmother’s separately. Thanks!