Help picking a plug in or module for Avada

I bought Avada theme

Now what I need is a plug in or add on that will allow me to do the following
Create not only a Global overall calendar or events list for the site and everyone on it but also for small groups specifically

My site is about a city
I will sell sections to small local businesses that want to have their business within mine
so they don’t want their own site

so mysite.com/theirsite

there will be several I hope

the thing is I want to be able to create a calendar of upcoming evets or specials specifically for each of them viewed while in their section not in another businesses section calendar

I want to be able to decide which of those show up globally or not

and thoughts on options for this?

thanks for the input and the sharing of experience