To clarify, has the deposit been reconciled yet? Was the payment recorded after the deposit date?
If not, then you can add the payment to the deposit. Below I've included the steps to do this. However, if the deposit was already reconciled or the payment was recorded after the deposit date, then you won't be able to add the payment to the deposit.
Let's get started:
1. From the chart of accounts, open the register of the account that has the deposit.
2. Find the deposit and click on it. Then you'll choose Edit to open the deposit.
3. Select the missing payment to add to the deposit.
That's all there is to it. Please let me know if there's anything else that I can do for you. I'll be just around the corner. You can always reach out to the Community or me anytime you find you need help. Take care and have a good one!