I-140 approved with Employer 'A' & changing multiple employers.

[premchn]

My I-140 was approved with my current employer ‘A’. I got my approval last year in Jul’13. Now I am planning to switch to employer ‘B’. My query is, in case if I don’t like the new employer ‘B’ and want to switch to another employer ‘C’ say after 6 months, will it be possible for me to port my PD to new employer (C) and get 3 years extension based on my I-140 approval from my first employer (A).

Please let me know your comments on this.