Change Request - Required input per department.

Basic required workflow:

• Sales department receives a set of PDF files from the customer for specific shapes. 
• Different departments must, for each shape, give feasibillity comments, and Approve/Reject if the shape can actually be produced.
• Based on input from departments, sales can make a quote to customer.

I am setting up a Change Request Type:

1. Header
1. Controlled by salesman (Status: Open/Completed)
2. Lines
1. Attachment drawing
2. Department specific attributes (Each department is required to enter specific information for this department: Design, Die Shop, Fabrication)
3. Status: Completed/Cancelled.

I have the basic workflow running, but needs some advise on the following: