When a smallcase you hold has been rebalanced, you will be notified by email and app. You can also subscribe to WhatsApp updates as well.
Steps to apply rebalance:
From your Investments page, click “Rebalance” where available
Review the update and make changes by clicking on "Customize"
Confirm the update to review and place orders
Your smallcase will be rebalanced only when you confirm & place the order, it will not be done automatically
You can skip the update if you do not want to apply it
Your SIP (if active) will also be updated to match the new constituents