Am I missing something or is it not possible to run multiple instances that use different data sources? If I want to use a Calendar add-in on, say, another site in my Site Collection I can't remove the data sources that I don't need from my first calendar add-in - if I do they disappear from the calendar that I already created for another site.
The on-line guides are a little bit light on detail in many respects - and it woud be great if the on line help guides could also be in .pdf format.
Data sources can't be separated between site collections, but you can choose specific calendar for a site page.
You can see how to do it here: https://www.virtosoftware.com/manual/calendar-app-for-sharepoint-online/choose-specific-calendar-for-a-site-page
Please find the pdf documentation in the attachment.