Currently, when adding a new line item to an existing payment plan with percentage-based payments, it retroactively changes the total for already-paid invoices. This requires disabling auto-send and manually generating drafts for all future payments.

Requested Solution:

Enable adding line items to payment plans that only affect future unpaid invoices, maintaining the original amounts for invoices already paid while automatically including new items in upcoming payments.

Current Workaround Issues:

Must disable auto-send feature

Requires manual draft generation for each payment

Interrupts normal recurring invoice flow