You can make changes to the stocks (add or remove stocks) & change weights of a smallcase before buying it, by using the Customize feature. When you customize a smallcase, you will not receive any rebalance updates made to the original version - so only customize a smallcase if you're completely sure of the changes and the subsequent impact.
You can customize a smallcase from the Stocks tab of that smallcase page

And then follow the same steps as in Creating your smallcase
The fees for buying a customized/created smallcase are the same at a flat Rs. 100 + GST (18%) for each smallcase. No additional charges from our end when you invest more, add/remove stocks or exit your smallcase
Note
- You can only add NSE stocks to create/customize your smallcase
- Your smallcase will be private and will be visible only to you