Hi Derek, Wim, everyone,
thanks very much for your replies.
@ Derek: yes it's true, I could build a workaround, with the level one terms linking to different sites, but that would be unnecessarily time-consuming... but I will try it anyhow, for I don't have a proper solution so far.
@ Wim, the convoc module you have on your site is exactly what I need. Unfortunately I am not able to write a module like that myself. Is anyone by any chance interested in doing so, or is there already a module out there that can handle conditional vocabs?
I think a module like this would be *very* useful for the Drupal community, and would be appreciated by a lot of people, don't you?
Thank you,
Laura