Under the Child Snapper Tests Extension, click into the Parent-Child Analyzer button and tool will show up as a new dialog window.

Visualize Parent-Child in 2D/3D

The dialog's tree view will only populate when a Snapper with parent-child relations is selected in the drawing. You can find these Snappers by enabling the Visualize Parent-Child in 2D/3D toggle:

Enabling this will show a yellow bound on the root parent of the group, and the other bounds are colored black.

Selecting Using the Dialog

Clicking on a tree view item will select the child snapper in the drawing, and vice versa.
If the Visualize Parent-Child in 2D/3D toggle is enabled, the bound will be colored in dark blue. 

Double-clicking on a tree view item will open up the Inspector respective of the Snapper chosen.