B2 visa application for 2yr old in india for separated parent

I have a scheduled a B2 visa interview for my Sister-in-law’s daughter, who is 2 years old. My sister-in-law is already having b2 valid visa.

Now she is living separated from her spouse. No court case filed for divorce. And having no contact with her husband. She would like to travel to US with her daughter during summer holidays.

What are the documents to be provided for this scenario and please let me know the procedure to get the visa for her daughter.​