Here’s a line from the Just Enough Planning Guide
There’s a saying that a camel is a horse designed by a committee. This seems like a particularly hard knock against the camel, but the point is well made. As you expand the number of people involved in planning, you run the risk of creating internal inconsistencies and unnecessary complexity, and, worst of all, you could lose sight of your campaign objectives. The key is to keep it tight and keep it small, but empower those on your team to do the work and trust that they will.
They identify 4 common roles for people to be part of the process: Input Givers, Decision Makers, Hard Truth Squad, and Buy-In Givers.
This is a useful framework. When thinking who you need to have on board, also consider how you need them on board and what role they need to play.