Suggest me the best Solution

 

The best method to combine multiple PST files manually then I would suggest the KDETools PST Merge. It merges the PST files in all Versio of Windows and Outlook versions.

 

PST Merger Tool is the professional software to Combine Multiple PST Files into One and remove duplicate emails from merged PST files successfully. The Tool allows you to Merge PST and its data items like contacts, calendars, notes, journals, etc. into a new single PST file maintaining data integrity without any loss.