Re: Adding More Creditors
You can file an amendment with the court. If the bk has already been closed, the fee the court charges for reopening & filing an amendment will be more than if the bk was still pending when you filed the amendment. Usually if you didn't list a creditor in a chapter 7 no asset case, there has been case law that the unlisted creditor debt will be discharged though not always.
You really might want the help of an attorney - they know how to do this. (However, you can do this on your own if you believe you can do it w/o an attorney's help.)