Service Request Process Integration

We are using the 'Process Integration' in Service Requests to open a related ticket for a separate part of the request. For example, during onboarding, if the requester selects the new user needs a laptop, the process will open a separate ticket to have the laptop assigned and setup. This second ticket is added as a related item so they are connected.

Part of the process has a requirement that the requester needs to add an attachment to an Attachment field (process field) on their initial ticket before submitting it; we then need the system to add the attachment onto the second ticket it's creating.  The ticket creates fine, but the attachment doesn't follow along.

Any ideas how to make that work?

Here are some screenshots of part of what we have in the Process Integration:

Attachment field name is "Yes (Attach DD Confirmation)":

I see on the API Documentation (here), at the bottom it has something about Attachments needing the content type ‘multipart/form-data’ instead of providing json or xml, but that content type isn't an option in the list, so not quite sure how to make that work either.