Your question is a bit confusing.
In the example you showed name “What I need to do is” you show a Canvas, which can hold as many as Widgets as you want.
However in your initial question you are asking to have the widget as a child of another widget. Which is a different story.
So if you want to replicate what’s on your “What I need to do is” screenshot simply drag the widgets you want on the Canvas Panel instead of on the Widget RadialBase.