This is the most direct approach. Reach out to the CMC Vellore admissions office by phone or email and explain your situation. Ask them if there's any possibility to change your course preference after registration.

If contacting the admissions office isn't feasible, you might have to wait for the seat allocation results. Based on your score and preferences, they will allocate a seat in one of the two courses you selected.

• If you get a seat in your first preference course (congratulations!), then there's no need to worry further.
  
  
• If you get a seat in your second preference course, you can then decide whether to accept it or explore other options.
  
  https://www.careers360.com/colleges/college-of-nursing-cmc-vellore
  
  I hope it helps!