Atom Techsoft OST to PST conversion is not a big task. You can search on google and you will get a no of third party tools like OST recovery, Atom Techsoft OST to PST converter. There are some manual solutions too but somehow they have some disadvantages too. I know about one Atom Techsoft OST to PST converter because I also faced a problem when I needed to change OST to PST. It is really an amazing tool. It can recover whole data with all the email attachments. You can also try it before purchasing it because it's demo version is free.
I think you should go with the perfect OST to PST Converter solution that permits users to save and open your OST database into Outlook PST file format with complete items like calendars, emails, address book, etc. This software well works on all versions of MS Outlook and Windows versions.
For more information: https://www.toolsbaer.com/ost-to-pst-conversion/