Sometime it’s better to slip it under the rug and just replace the speaker with someone else who can also contribute to the discussion and highlight the new speaker value making it sound even better then the first one.

Take a deep breath. This has happened to me twice. The first time, I was notified the night before that the keynote speaker could not make it. We had the company CEO fill-in and tell a story about the origins of the company. It worked. The second time was illness related, and somebody else on the team proposed that we have the person give their keynote remotely. Not ideal, but it worked!

Cuando un orador principal no está dispuesto a compartir el escenario, es importante abordar la situación con diplomacia. La comunicación previa es esencial: identificar los puntos clave de cada intervención y buscar un equilibrio que permita a ambos destacar sin restar importancia al otro. A veces, dividir los tiempos o asignar roles complementarios puede ser una solución efectiva. Si bien puede ser un reto, manejarlo con tacto y enfoque colaborativo puede transformar un posible conflicto en una oportunidad para enriquecer la experiencia de la audiencia.

If they're part of your team then conversations should already have taken place prior to the event along the lines of 'there's no 'I' in team' - however, if they are a special guest from outside the firm and this is their rider + the value of their appearance exceeds any questions of ego, then go with it & make a big thing of their influence, maybe along the lines of 'this stage isn't big enough for the both of us'?!

I just wait for his part of conference and after I do my best in way the atendees forgets about what he said. There isnot dilemma.

Stick to the Schedule: Politely but firmly reinforce the time limits and transitions in the conference agenda. Offer alternatives, such as giving the keynote speaker extra time before or after their talk without encroaching on others’ slots.

Notify him ahead of time of his/her alloted time. Send notes to him/her as reminders when his time winds down. Get a respected senior colleague tease him off the stage when his/her time is up While it is within the timeline of the keynote address, allow him enjoy the platform. A feedback from the audience may help him/her reflect on his/her performance. I hope this helps.