Varsha, you haven't mentioned whether it is for NEET UG or NEET PG All India Counselling. Neverthless, you can add any number of choices to your 2nd Round of Counselling. There is no cap on no.of choices you can choose and lockdown. The seats are allotted based on merit come preference. But you just need to make sure that you need to lock your choices after selecting them. Or else the server will lock them for you by 5pm on the last day of the Choice Locking.