In order to switch between different media's within one print job you need to define the media for each page in the layout section of the workflow.
In this Inspire Workflow Invoices layout we have two pages. "Invoice_Consumer" and "Terms_and_conditions".
For each page you need to define a sheet name.
A sheet name can be dynamically chosen by a variable. But in this example we will use fixed sheet names. See the following images.
Sheet name A4White for the Invoice_Consumer page:
Sheet name A4Pink for the Terms_and_conditions page: