If you are looking for the best solutions to merge calendars in Outlook then you can go through this informative article that I've recently explored. This article will provide you the complete solution of the manual method to accomplish this process effectively. However, the manual approaches are time-consuming as it involves several steps to perform effectively.
In such a scenario, you can use the Cigati PST Merge Toolthat facilitates to combine multiple PST files into a single file without the risk of data loss or file corruption. The software offers various merge options like Join, Merge, and Merge Contacts, and supports all versions of MS Outlook. It also enables you to protect your resultant PST file by applying the user-defined password. For analyzing its performance, try its free demo version.