According to the PBA Guide, one of the techniques for managing stakeholder engagement is recognition and rewards, which can be used to motivate and appreciate the team members for their contributions and achievements1. The PMP Exam Content Outline also lists recognition and rewards as one of the tools and techniques for leading a team2. Awarding certificates of appreciation is an example of recognition and rewards that can boost the team's morale and performance. Informing the team about the delivery pressure from the project sponsor may increase their stress and anxiety, which can negatively affect their performance.
Sending a formal notice to team members instructing them to maintain performance may be perceived as a threat or a punishment, which can also demotivate the team. Hiring a few temporary team members to help with the additional work may introduce new risks and challenges, such as communication issues, learning curves, and integration problems, which can delay the project further. References:
* 1: PBA Guide, Chapter 6, Section 6.4.3.5 Recognition and Rewards
* 2: PMP Exam Content Outline, Domain II: People, Task 8: Lead a team