If I get my I140 approved through employerA and quit the job after getting the I140 approval and go to employerB . my questions are:1)Can employerB use approved I140 from employerA to file for my 3 year H1B extension 2)Do I need to be on payroll of employerA for them to file for I485 if and when it gets current.3)Can I keep on using this approved I140 from employerA to get multiple subsequent 3 year H1B extensions although visa petition will be filed by employerB 4)What happens if employerA happens to go out business while I am busy making my career and rising the corporate ladder as and when suitable opportunities show up and hence change employers to C and D - I mean can C and D file my H1B petition but use approved I140 from A as grounds for H1B extension.What are the risks involved.