The answer is No. The Information Bulletin says that the information entered by the Candidate remains final and no changes will be thereafter entertained. If you select OBC-NCL as your Category, OBC-NCL will remain your Category. If you cannot submit your relevant documents, your admission  will stand cancelled but you will not be considered under General Category. This is because the merit list is prepared even before the counselling and the document verification happens much later. So it is not possible to change merit lists according to the document verification.