You can combine (i.e. merge) several user database files (extension *.mtu) into a single new one. This is possible in two different ways:
For one, you can do so in the User Database Manager: Please press the "Combine" button at the top, mark the mtu-files you would like to combine in the "File/Open" dialog that is displayed, and press "Open".
Afterwards, you will be asked about the directory and file name for the target mtu-file, so please make the appropriate selection and press "Save". The merging of the files will now be carried out; a corresponding progress window will be displayed that will close automatically when the merging has finished.
As an alternative to using the User Database Manager, you can also run the menu command "Combine user databases (*.mtu)", either in the "File / Combine" or in the "Database" menu. Afterwards, the procedure is the same as described above when using the User Database Manager.