How to Create a Singular Outlook Calendar from multiple emails w/ different domains and dif/ tenancy

[Izabel_Barros]

I am a consultant with 4 outlook accounts form different domains and different tenancy with four independent calendars that I keep forwarding invites to one another, which has been driving me nuts!

Any idea on how I could automatically share my calendar across accounts without forwarding the invites in cyberspace?

[#2]

BTW Overlay and side-by-side are not an option as people won't see real availability across accounts....