Once you have bought your smallcase, and want to increase your exposure to it - you can invest more in your smallcase
From your Investments tab, tap on the smallcase you want to invest more in and then tap ‘Invest More’ at the bottom. (If you have a SIP due, the Invest more option will show up as a green button under Performance)
The Invest more page helps you buy more of what you currently hold. That is, it will have a minimum amount to maintain the weighting scheme. You can increase this amount to invest whatever amount you like in the Confirm amount box. The extra amount added will get auto adjusted to the closest amount required to maintain the weights
Once you tap on the Confirm amount, you can review the order and Confirm the order.
You can use this functionality to double down on your investments anytime you like. You can also invest more regularly through SIP.