Pulling information on Child tickets from an existing Parent through API/IpaaS

I'm trying to build a workflow in IpaaS that involves a step where it checks a parent ticket, then determines the current status of the child tickets attached to it. However, this doesn't seem to be inherently possible. When pulling the ticket JSON through IpaaS or the WebAPI, each child ticket knows that it has a parent, and the ID of the parent. However, the returned information on the parent *does not* know which tickets are it's children.

One method that could work is using the "Get All Tickets" call and sorting through to pull every ticket with the correct parent ID, but that seems extremely overkill for information that should be included. We've dodged around this issue in the past by calling a report in Analysis and filtering it based off of that same sort of idea but that's again, far more steps than should be needed for such a simple operation.

Am I missing something on how to do this?