How to show group calendar events on everyone's personal calendar?

[Anthony-123]

I have an org-wide team where I've created an event for July 5th. I can view that event in the Group calendar and I've published it on our SharePoint site. 

How can I make this event appear in everyone's calendars? Do I have to invite every individual?  

Since this is an org-wide group, I would think adding the event to the group calendar should make it appear on everyone's personal calendars. Evidently, that's not the case.

If I invite other groups, would the event only appear on that group calendar or might it also appear in personal calendars? 

[#2]

Teams-enabled groups, including those belonging to org-wide teams are "hidden from Exchange clients" by default. Thus they will not appear in Outlook/OWA, and users cannot manage their "subscription" settings. You as the admin can add everyone to the "subscribers" list or toggle the AlwaysSubscribeMembersToCalendarEvents/AutoSubscribeNewMembers flags for the group.

[#3]

And if I enable AlwaysSubscribe, would that make the group event appear in their personal calendars?

[#4]

Yes, the caveat is that it works only for newly-added members.

[#5]

Ah. That's a pretty significant caveat rendering this solution null.

[#6]

You can manually "subscribe" existing members as the admin, check the Add-UnifiedGroupLinks cmdlet.