Putting events multiple calendars

I need the same events to be in multiple calendars to access on my iPhone and iPad. 🤷‍♀️ 🤗🙏

Since my mom has been recovering from Cancer as well as Brain Surgery from a bleed my sister & I have been taking care of her w/her Many appointments. I just had a thought when I checked for next weeks appointments…why are the 3 of us jumping over ourselves to keep appointments lined up?? 🤷‍♀️

I added a new calendar named Mimi, sent it to my sister &…oh oh, I can’t also include the appointments on my Family Calendar to let my crew know what’s up and where we will be. Would be Very Helpful. I honestly did not know it could Not be done until Just Now. 😢