prev next for child category only

Hi there,

i currently work on a project with a lot of categories. each posting is asigned to the parent category AND one child category.

For the single.php i need prev / next links only for the child category. But the default templatetags previous_post and next_post display the prev / next links from the parent category. is there a way to put some php hackery around that tag to make it work with child categories?

would be amazing if someone can help me! thanks!