Changing skeleton size

Hi,
	
	I'm writing an app that will modify the dimensions of character bones in an FBX
file. The FBX file contains a boned and skinned character and one frame of
animation where the character is in the default (T) stance. The character inside
the file has been characterized using MotionBuilder 7.5. I'm using FBX SDK
version 6.1.0.
	
	Working from the examples, I have loaded my fbx and changed the default
positions of the bones. I have then saved the resulting fbx. 
	
	Using breakpoints during debugging, I check that the translations have been set
on the nodes like this:
	
	KFbxVector4 defaultT(0,0,0);
	pNode->GetDefaultT(defaultT);
	pNode->SetDefaultT(lLocalPosition.GetT());
	pNode->GetDefaultT(defaultT);
	
	e.g. For hips:
	Before the call to SetDefaultT, 
	     defaultT = 0, 43.5, 0
	After the call, 
	     defaultT = 0, 1.06, 0
	
	This is the expected result. However, when I open the saved fbx in
MotionBuilder, the bone offsets are still the same as in the source model. 
	
	I appreciate that setting the bones translations is only the first step in my
task - I'll also need to scale them at a later point. I did expect to be able to
reposition the bones using the above code though.
	
	I have been scouring the examples and forums all morning, but am unable to find
anything that might explain to me what is going on. Can anyone help?
	
	Regards,