To merge multiple PST files you can find many tools. Merge PST Tool is one of the best & suitable software. This software merges multiple Outlook PST files in a quick time. It works with all the versions of Windows OS and MS Outlook and users can add ANSI as well as UNICODE. PST file type to merge. It conserves the data and ensures the folder hierarchy of PST files in the combined procedure. There is no file size limitation and you can merge PST files of any size.
You can easily merge your multiple PST Files into Singal PST file. You can also try third-party PST Merge Tool. I would like to recommend you use the third-party tool its easily merge your multiple PST file in a single PST file format without any issues. You can also try the free trial version of this tool. Read More:-http://www.sametools.com/merge/pst/