Unanchored Frames within a element

Hello FrameMaker community, 

i'm currently struggeling to find a way, how to get graphics that are inside an element or get the parent element of a graphic. Given is the following structure:

The Graphic element contains an unachored frame with one or more graphics (XML-Output):

<GraphicContainer>
	<Graphic>
		<xy:Graphic file="xy.eps">
			<fm:Frame>
				<fm:Inset/>
			</fm:Frame>
		</xy:Graphic>
	</Graphic>
</GraphicContainer>

There are two options that I have for my usecase:

1. Select the frame and get the parent element.

I can receive the selected graphic, by executing the following function:

graphic = doc.FirstSelectedGraphicInDoc;

But i can't find a way to find out which element contains this frame/graphic.

2. Select the "GraphicContainer" in the structure tree and get all children graphics. 

I've tried to receive the children frames by executing the following lines:

tr = doc.TextSelection;
var ti = doc.GetTextForRange(tr, Constants.FTI_Frame);

 But the received object (ti) is invalid. 

Can anyone explain me, how framemaker handles graphics inside elements or give me an example?

Ty and best regards 

Marlon