Currently working for Employer A.

H1 Start Date: Sep 2005 (Employer A)
Labor and 140 approved by Jan 2010 (Employer A)

H1 Remaining ( 18-20 months months)

Scenario1: If I change to employer B from employer A now, how long an extension will I get on my H1? I thought it would be additional 3 yrs based on the approved 140 at company A?

Scenario 2: What happens if I have to change to a third employer C witin 6 months after joining employer B? Would I still be able to use approved 140 from employer A to get 3 yrs extensions?

Thanks a lot.