To create sub-calendars and calendar access links in bulk, you can import a CSV file.
Go to calendar Settings > Import Events, then click the sub-calendars link:
When importing from Excel:
Then you save as a CSV file and use the Teamup import tool:
Here is an example file for importing sub-calendars in CSV which you can use as a template:
This article lists the supported fields for CSV format.
Related ticker: A template for importing events from Excel to Teamup.