It is possible to access multiple Eventbrite organisations, that you have a relationship with, from one API key and hence display combined events.

There is a little bit of configuration required within Eventbrite.

1. Decide what user  s going to be across multiple organisations, this may be best to create a new Eventbrite user under a different email you have access to e.g. newuser@example.com, it doesn’t need to create any events, just needs to exist
2. Log in to each ‘main account’  Organization Settings > Team management  https://www.eventbrite.com/organizations/permissions  and invite newuser@example.com
3. From the new user account accept invitations
3. Then use  the API key of newuser@example.com  which then will include all organisation invites / accepted

You can see this in settings e.g.

Now when you display the events e.g. [wfea ] all events from all orgnanization teh newuser is a team member will display as if one.

In the Pro version it may be that you need also to split the events, e.g. you may have a combines page and individual organisation pages. On eth individual pages you can use ( based on your own data )
[wfea organization_id=285905431035 ]
and
[wfea organization_id=147852730692 ]