Form field types should include a Project Member field type where you can pick either a specific person from the Project users list or a Company from the list of Companies involved in the Project. For example, you are creating a form that needs to reference 3 different stakeholders that are involved in the Form, it would be nice to have a field type that would allow you to pick from the Project participants to include a reference to the form that would also notify them, like the Watcher field.