Thanks a lot to all contributing to this topic.
This worked for me:
<item caption="Isobaren" title= "Isobaren heute">
<item caption= "Isobaren &#169; MeteoGroup" title="Isobaren1" link="wxisobaren.php"/>
<item caption= "Isobaren &#169; DWD" title="Isobaren2" link="wxisobarendwd.php"/>
</item>
Probably running in issues now with the language translations. Anyway, it's very much fun.
Cheers