Influence Without Authority
Here’s a generic project approach when many constituents and you do not have direct authority over resources:
Socialize the project at various forums/meetings; maybe need to do multiple times for it to sink in and/or to hit all the groups and give opportunity for people to voice concerns
Have small peer-group sessions to give people the opportunity to voice concerns that they may not feel comfortable voicing in the large forums.
Create task groups / work streams etc. to get the work done; groups are of limited size 3 to 5 people per group.
Gathering key people from the task groups to share progress, obstacles, and alignment etc.
Send task groups off to do work; bring back key folks to meet as needed and then send them back out again.