Idiom for unheard individual voices banding together to become a group with a voice that is heard

Consider for example many tiny little charities that are too small to have their concerns recognized when there is a threat to them. They band together and create a bigger organization and through that, they are taken seriously and begin to be consulted. What is a quick and elegant way of expressing this strategy?

Union is strength comes to mind:

This proverb means that ‘sticking together is a source of strength’. If people join together, they are more powerful than if they work by themselves.

(The Free Dictionary)

there is strength in numbers Merriam-Webster defines this as:

used to say that a group of people has more influence or power than one person