The best way to get buy-in from any stakeholder is to get them to join you in the ceremonies and participate in the day-to-day Scrum execution. Organised presentations and training is also essential to create a feeling that the transition to Agile in the best approach. On the other hand, the need to foster the Agile atmosphere and prove that it is not FrAgile, does not give you carte blanche to ignore the feedback of those stakeholders who do not necessarily see the value.