Visitor Visa Sponsorship when Have L1B Visa and H1B Approved at the last moment

[ChandreshHingu]

Hi,

I travelled to US on L1B Visa from Company A and I applied for Visitor's visa for my Parent-in-law. They have interview in this week(on 17th Jan,2013). Now I have got the approval for my H1B Petition from Company B on 3rd Jan,2013,

Questions:

1. Do I have to change documentation(Employment Letter, I-134 Sponsorship Affidavit etc) from Company A to B?

2. Can I still work for Company A untill their Visa Interview is done and join company B right after the interview date.

Please help as I have only 3 days left before the visa interview.