Yes, multiple users can work on the same program and proposal. By default, all users have access to a program and proposal, regardless of to whom it is assigned. Assigning users to proposals as Salesperson, Sales Coordinator, etc. is to provide specific contacts for the program clients AND to track employees assigned to each program in reports. It's easy to collaborate with colleagues on a single program, just be sure to take advantage of the internal notes areas throughout the system so collaborators can be "on the same page" and ensure all client requests are met.