H1 B extension with current employer and transfer H1 with new Employer Parallel

Guys,

need your help to understand scenario !!

my h1 b is approved for only two months due to SOW was until this DEC. so my current employer is filling extension next week. meantime i have offer from new employer and they are also start doing process for my h1 b transfer. my new employer is not ready to allow me work on receipt notice so obviously i need to stick with my current employer.

Question:

  1. what if extension/transfer gets approved first with my new employer before my current employer extension ? do i need to travel abroad to get it stamped in order to activate h1 b with new employer ?

  2. what in the case of reverse situation that mentioned in step 1( current approved first and later new employer then) ?

  3. what will be happened if my current employer gets denied first before approved with new employer and if new employer approved first then current employer gets denied then ?

appreciate for all your help !!

Thanks,

Maulik