Once your application package is submitted, you are unable to further edit it. For this reason, you should ensure that your application is filled out as thoroughly and completely as possible and that you have gathered all required documentation ahead of time.
If your application package is missing required supporting documents, you may receive a notification from an immigration official requesting additional information or documents.
If additional evidence is requested by the visa office, your application processing will be put on hold. However, in some cases missing documentation will cause your application to be automatically rejected. In this case, you would have to re-apply for the visa. A qualified immigration lawyer can review your application prior to submission to ensure you have the best chances of your visa being approved.