Trouble adding language track into mkv file

[kruuth]

How do I add a new audio track to an MKV file? I have audio for Russian, German, Czech, and Estonian and I want to add English. So far the only way is to extract and then build a new MKV. WHen I do this the audio is out of sync. Is there some way to fix this?

[poisondeathray]

Did you try mkvtoolnix? Open your existing mkv file, add the new audio