When the community got into a conflict, the siblings arose and they tried to resolve the conflict. They tried everything in their armor to end this conflict once and for all.
The community was arguing that the sister of Joyce is a girl and cannot take part in the protest. But Joyce was saying that she is powerful as any other man and she is my other brother and her strength and wisdom could be used in the protest.
This is how he convinced everyone and everyone was convinced soon enough because every other positive argument added to the confidence of the protesters because they were protesting for equal rights and they were standing against the face of discrimination against everyone.
Image is taken from the prompt