you directly become eligible for all merit based courses, if you have not filled the form , however, if separate form had to be filled in order to secure admission in b.com (//b.com) then it is a problem, since you won't be able to secure admission in b.com (//b.com) . If a single form is released for both and you chose BBA, then you directly become eligible for b.com (//b.com) as well .