To change a Brussels Airlines flight, visit their official website and log into “My Booking” using your last name and booking reference. Eligible tickets can be modified online by selecting the “Change flight” option. Fees and fare differences may apply based on your fare type. You can also call Brussels Airlines customer service for assistance. If your ticket is part of a group or booked via a third party, changes must be handled through them. Ensure changes are made before your original departure to avoid losing the value of the ticket. Terms vary by route and ticket class.
https://www.changebookings.com/change-booking/how-to-change-brussels-airlines-flight