XDataClient.Post with nested lists

I have an entity with a list of other entities, each of which last lists of other entities etc.

There is a depth of approx. 6 levels in the structure.

When I call an xdata service with a base level entity as parameter, XData seems to be only serializing a few levels of the structure (in my case the first 3). 

Is there an equivalent of XData-ExpandLevel that I need to use to tell XData to serialise the deeper objects ?

Or is there something else that could cause this behaviour ?

This was a bug in my code.
I hadn't declared the lists correctly (using a proxy), and hadn't initialised / freed them correctly using SetInitialValue/DestroyValue.
All working now !!