Parents and Brother B2 visa questions

[kaavu]

I plan on applying visitor visa for my parents and brother for my graduation ceremony in US. My parents are retired from government jobs.
1. My brother is single, engineering students in a highly reputed college in India, still has 2 years to graduate. He has summer break from his school during the time of my graduation ceremony. Is it a good idea to apply for his visa with my parents, so that all three of them can visit me together?
2. Can I make the payment for visa application from my Bank of america account in US? does it have to be in INR?
2. When I go to payment options on ustravel docs, it is giving me only one option of making the entire payment of three candidates all together. SO, will it be the same receipt number for my mom, dad and brother? Or Can I make the payments seperately?

(Note: I have a younger sister too, studying in India, we are not applying for her visa, as she cannot get any vacation from her study.)

[kaavu]

Any views????

[peace999]

You know a lot depends on the trend and the interviewing officers, since B1/B2 decisions are so discretion dependent.

At times, they would hear the word " retired' from parents and deny.

In your case, you just graduated, your parents are retired, siblings are students,
who will be funding the trip?