Setting menu trail of subpage of a node I'm trying to have a subpage for a special content type. Everything is working fine, also the breadcrumb is working now.

Only the active menu trail isn't showing up and I really don't know how to hack into the right process. Are there any special functions helping me with this problem?

I tried menu_set_active_trail(), but having problems with nodes placed in a menu by the user where I cannot get the previous menu trail for the node itself.

I hope you can help.Thanks in advanced!
The function you need is menu_tree_set_path.  It will be released with Drupal 7.9.

If you can't wait, the workaround is to use this code in hook_init:

&lt;?php
$item = menu_get_item();
$item['href'] = '&lt;the href of an existing menu link&gt;';
menu_set_item(NULL, $item);
?&gt;