Below is the steps of adding seat after the confirmation.
Step 1: You have to login into you udChalo account with registered email id or phone number and click on "My Bookings"
Step 2: Once you have clicked on my bookings then you can select the booking in which you want to add the seat.
Step 3: Once you have selected the booking then click on "Show More"
Step 4: In the next page you will be able to get the an option of "Add+"
Step 5: Once you have clicked on Add you in the next page you will receive the seats available. Once you select the seat click on "Continue"
Step 6: In the next page you have to make the payment for the seat and the seat will get added to your booking. You will get the confirmation on your email id and phone number.
Note: udChalo doesn't charge anything for this service apart from Airline Charges. You can add seat through M-Site/M-App only.