This means invite everyone. Do not select or appoint. Let others decide whether the decision will impact them or not. This sounds extreme, but this mentality is necessary to really be collaborative. Work with others to establish formal processes to allow this inclusion.
Collaboration takes time.
Make this understanding a priority of the district. Poor decisions cost more time in the long run than collaboration. Collaborative leaders must be able to listen authentically. What they hear should impact and even change their thinking. Without this ability, a superintendent will not be trusted.