Maybe MS Flow can help. Check this templates.
It is hard to sync calendars in both ways, and in outlook there is no trigger 'When event is deleted', but all new meetings you can send automatically to one calendar.
Same problem for us with no solution yet.
Our situation is that we are one of 2 vendors working with a client.
All 3 organizations have Office 365. Most of us in the 2 vendor companies have acquired accounts in the client's org but all of our email and meetings get sent to and from our vendor accounts—so though we can see calendars for our client colleagues, we can't see each others' calendars.
If we could automatically sync our vendor account calendars with our corresponding client account calendars—everyone could then always see current calendars of everyone on the project through the client accounts.
One may ask, "Why doesn't everyone just use their client addresses for everything on that project?" The problem with that is actually that we're also using Teams but our client doesn't have everything we'd need enabled on their instance, so we're using one of our vendor Teams instances as the working in progress home for the project meetings, messaging, and file share. If we all just used our client accounts, they're all treated with Guest permissions which have many features unavailable and we'd be stuck in the virtual lobbies of our own meetings.
So much cumulative time is wasted every day, just asking when we have open time. It is currently 2019, can't this situation be solved?
