Paystand can support Parent/Child Payments through both the brandable interface (billing portal) and SMART Lockbox via Consolidated Invoices.
If the NetSuite customer has a hierarchy of sub-customers, we offer a feature that allows statement checkouts to be sent out (given a plan setting is in place), that will show all open Invoices for the parent and all of their children.
It can be paid with a single payment, and using the consolidated payer/payment feature in NetSuite (something the NetSuite customer needs to have enabled), we can apply the payment to all of the Invoices across the sub-customers.