I have a question about who is responsible, appart from the Project Manager, for determining the stakeholders´roles. I´m not sure if it´s only the Project Sponsor or any other stakeholder who can help in this activity.
It depends what you mean by "roles". Responsible for Stakeholder management is, in my understanding, the Project Manager, but he or she should get input from as many places as possible, as descriped in PMBOK 184.108.40.206, 220.127.116.11 or 18.104.22.168 on Expert Judgement
Moderators: Yolanda Mabutas, Ahmed Amin, Scott Gillard, Mary Kathrine Padua, ERIC BARTLETT, Gail Freedman, Kevin Nason, Steven Mudrinich, PMP, Mark Wuenscher, PMP, John Wolverton, Tracy Shagnea, PMP, Jada Garrett
This interview with Simona Fallavollita (LinkedIn Profile) was recorded at the magnificient Project Management Institute (PMI)® Global Conference 2017 in Chicago, Illinois. We discuss the how, what, why and when of the changes that are coming to the PMP exam.