140 Porting and Future employment

[504321676]

my 140 on EB3 is approved from my current company A and currently working with them on H1B.

i got on offer from another company B as Future employment and they are ready to file EB2 and can wait for my joining until 140 is approved and also they will be porting my EB3 Priority date.

Will there be any issues for my current employment with A ?

After 140 is ported and approved with Employer B , if i decide not to join B ,can i continue my employment with my current company A and any issues for my EB3 GC?

Appreciated for any guidance..