To Consolidate Outlook PST files into one PST files in MS-Outlook then try the KDETools PST Merge. It Combines several Outlook PST files such as Emails, Contacts, Calendars, Tasks, Notes and all. It Consolidates multiple PST files without any duplicates in MS-Outlook. Merge the PST file in ANSI and also UNICODE formats. Supports in all Version of Windows and Outlook. No needs for MS-Outlook installations. Merge password protected PST files in MS-Outlook.
More Info: https://www.kdetools.com/pst-merge.html
Click on Open & Export > Import/Export. Select Import from another program or file; click Next. Select Outlook Data file (. pst) and click Next
Combine Outlook files with all data or selected data with Merge PST Tool in just 4 simple steps. I have used this application a week ago and got fine results therefore, I would like to suggest you to use this application to merge Outlook data files into one PST file. It help you to join PST files without Outlook installation.
Visit here for more info: https://www.osttopstapp.com/pst-merge.html