how to merge icloud ical with my IMAP and Exchange calendars?

I have a problem that i got my Acuity Scheduling software connected to my iCloud iCal and my company calendar is IMAP with Hostgator and another is an Exchange account. I want to merge all of them into iCloud. how can i do that ?

The reason is that i need this as to sync my other appointments up to Acuity, and its only connected to iCloud.

Your help would be much appreciated.

Thanks so much.