Merging all visible Calendars on iPhone (& sharing)

All the existing posts on this subject are rather old and refer to the “import/merge and deleting” of the existing calendars that you’d like to merge. I’m hoping Apple has come up with something more practical.

I have multiple calendars used for different purposes and clients, i.e., “google calendar”, “Microsoft exchange”, “subscribed calendars” and my IOS. IOS is my “main calendar” where I add appointments. Others add appointments to the non-IOS calendars. I can see all my appointments from all the calendars on my iPhone and iPad.

here’s the challenge…

I would like my assistant to see what I see without having to share each of the individual calendars with him (and thereby making a mess of his calendar system too).

Without having to export & then importing the non-IOS calendars to the IOS calendar (which then requires deleting the old non-IOS ones), how to I otherwise merge those appointments into my IOS calendar so I am able to share just the “master” IOS calendar?

Apple support’s ‘Quick Response’ referring back to a 12 year old merge & delete calendar support page isn’t helpful. LOL

Has anyone else figured this issue out? Hoping I’m not the only Mac, iPhone or iPad user that’s struggled with this.

Thank you for your thoughts!!!

Paul