Thank you for your reply, Kees.
Please excuse me for my delay in reply.
How about if answer the third question first, ''why do you want to combine backups?'' On about three occasions of reinstalling my computer's operating system, I downloaded new email to Outlook Express without first returning (''importing'') my backup data to Outlook Express. In order to have access to the old email from multiple backups and to read new email, I had to combine the backups with the email existing on the current installation.
My reply to your first question: ''how did you make those backups?''
I used the instructions from Microsoft Knowledge Base Article, 270670, ''OLEXP: How to Back Up and Recover Outlook Express Data,'' http://support.microsoft.com/?kbid=270670
It says:
Click Options on the Tools menu; click Store Folder on the Maintenance Tab; Select the folder location and then press CTRL+V and then click OK. On the Edit menu, click Select All. On Edit menu, click Copy and then close window. Create a new folder on the computer desktop with name ''mail backup.'' On the folder menu, select Edit and click Paste.
The data then appears in this folder. The folder can then be saved to a CD or external hard drive storage to be copied back to the computer later when a reinstallation of the system software has been performed.
In answer to your second question, ''How did you combine them?'' At the moment, I don't remember. I should have notes on the steps I took on a notebook hard drive that I do not have access to, at the moment. However, to ''Import'' Outlook EXpress data to my computer, I went by the instructions on the Microsoft link above, reversing the process, copying the data files back to the computer.
From my recollection, to import multiple data files to OE, I followed the procedure for each. I then discovered that I had many duplicates of emails. This, I believe, was because I had imported only one of the backups to Outlook Express, downloaded new email, and then decided to reinstall my computer system again, requiring to make backup of OE again. It seems that I could import the third backup to all of this without there being duplicates. But I believe I had been importing one of each of the backup files, on separate occasions, unaware that there were multiple backup files.
I believe the reason I got into this mess was I have been reading email from a desktop and a notebook computer. I download Outlook Express email only to the notebook. However, when I had problems with the notebook and was very busy, I went on the desktop pc, forgetting about what I was doing on the notebook with the several backups it had, etc.
Don