Hi everyone.
Still not willing to give up on my idea of using HA calendar to populate other calendars. 
Question: Is is possible to subscribe to the HA calendar from other ones - like IPhone calendar app?
Scenario: family members do all have their phones with personal events which should stay that way. We not want to put all events into HA.
But we would like to have ‚central‘ events (like waste collection, sports etc) managed by HA calendar and then populate those events into the iPhone calendar app of each one.
Still cannot believe that I am the first one with that idea … 
Therefore I hope someone much more smart than me figured this out.
Thanks all for any hints.
Great community and great system btw. !
It’s quite straightforward to set up with an external server, but I don’t think HA can act as a server for other devices - maybe I’m wrong.
I have a calendar on my Synology NAS, and use CalDav to push it to HA and to my Android phone. On my phone I can also have a local calendar for private stuff, and events from both can appear in the phone’s calendar app. Does that sound like what you want?
Thank you for your reply.
It is not quite what I have in mind.
Problem is that I have an older synology and cannot update to their latest DSM. The IPhones don’t accept connections to the NAS anymore - guess due to some security thing which Apple implements.
So the NAS is out or I would have to buy a new one which I don’t want
Cloud calendars are also not really an option because I don’t want to have the work events out there in the world.
My thought was since HA is running 24/7 anyway and offers the calendar, I could make use of it.
Seems like my scenario really IS a bit esoteric 