L-1 to H-1 transfer - URGENT

I am currently on an L-1 for Company A. Company B is filing for my H-1 transfer. In case I quit Company A and my L-1 gets cancelled, is my stay valid and can I work for Company B while my H-1 transfer is pending. What happens if for some reason my transfer gets delayed or rejected

I have exactly the same situation. Have you been able to obtain any info. I also need to trabsfer my L-1 to H1-B ASAP.

Thanks