H1 transfer complete . Decline to join


my H1b transfer process is completed along with dependent H4. However my old employer is doing the extension process

I am thinking of not joining the new employer. Is there any issue in declining the offer. Do I need to do i9 again with my old employer.is there any documentation to be done in the scenario ?

You can have any number of approved H1s at the same time and also you can work for any or all of your H1 approved employees at the same time. You are safe to work with any of your employees who got your H1