Use an XPath query to set a root node on the tree, either based on a search from the root of the content tree, or by using a context-aware placeholder.

A placeholder finds the nearest published ID and runs its query from there, so for instance:

$parent/newsArticle

Will try to get the parent if available, but will then fall back to the nearest ancestor and query for all news article children there.

Available placeholders:
$current: Current page or closest found ancestor
$parent: Parent page or closest found ancestor
$root: Root of the content tree
$site: Ancestor node at level 1

Note: The placeholder can only be used at the beginning of the query.