Thanks for your message.
Can you provide any update worth sharing with others here?
Originally I had created the action in Business Objects, under Manage Actions. This resulted in the system wanting a new window.
Instead I performed the following and it worked:
1. Navigate to Process Designer > Business Objects
2. Expand your module to get to Actions (in my case Incident Management > Incident > Actions
3. Select New Action
4. Name your action and Action Type (in my case, type = Update)
5. Allow Association with Window = True
Now I drag that automatic action out to the process and it is associated with my main Incident window. I can hard code fields in the Incident window when they meet the conditions of my decision object.