Hello Mary,
Thanks for reaching out to us!
I’m not quite sure how it would be possible to show events in the calendar without first importing or manually adding them. Either one or the other would need to be done.
If not that, then it might be possible with some custom development but that is way beyond the scope of our support.
For importing events from external sources we have Event Aggregator. There is no specific Salesforce import option, however there is an option to import events from Other URLs, though I cannot confirm whether it works with Salesforce or not. If you can provide me with a url to a salesforce driven calendar, then I can check if that works.
Is there anything else I can help you with?
Cheers,
Andras