There are three options.
1 - Create a formula url that will create x number of payment records based on the previous selection.
This will utilize the "API_AddRecord" function. You will just need to work the logic into the formula for how many times it redirects.
2 - Use a Quick Base Action to create the child records based on a trigger (i.e. adding the [# of payments scheduled]
3 - Webhook, that triggers a 'CSV import' and creates the records.
All of which will require a little know-how, but if you need more clarity on any lets us know.
