B2 visa for sister in-law

[anandpjoshi]

I am working on L1 for 2 years and my wife is on L2(EAD) working for 1 year. We want to invite my in laws and my sister in law with her daughter (going to school). They will stay for 1-1.5 months in US. My sister in law is not working in India but her husband will stay in India during their visit.

My questions are:
1. Invitation letter should be sent by me or my wife? (L1 or L2?)
2. Any other documents needed if I invite them?
3. How much are Chances of my sister in law getting rejected for visa?
4. Should all of them appear together or separately for the visa interview?

[immihelp]

1. Either way. Whoever is sponsoring should send the invitation letter.
2. Your marriage certificate to prove your relationship to your wife and birth certificates of herself and her siter to prove that they have common parents and therefore they are sisters.
3. That is really difficult to predict like that. She must show strong ties to the home country.
4. Doesn't matter.