Get children or siblings of node

Why is there no method that lets you access the private field "children" of SceneNode? Is there another way to do it?

Start by locating SceneNode and its private children field, then inspect the surrounding node-management API to understand how relationships are represented. Determine whether the issue needs public child or sibling access, or a documented existing alternative; done means the intended access path is clearly defined and covered by the project's relevant checks.

Written by the indexing model from the issue text.