You can add one or more additional steps to a checklist for a property or for a mission.
Add extra steps for a property
From the property page, click on Options > Add extra checklist steps
Once edited, click on save to apply te modifications to the next missions checklists associated to the property.
Add extra steps for a mission
From the mission page, click on Checklist > Add extra checklist steps
Once edited, click on save to apply te modifications to this specific mission only.