集思广益 Gather thoughts and widen benefit. To collect the wisdom of many and take in all useful views.
群策群力 The plans of the many and the strength of the many.
和衷共济 Of one heart, crossing together. To work together to overcome difficulty.
众志成城 The wills of the many form a city wall. From the Discourses of the States: “The hearts of the many form a city wall.”