Automatic Creation of LBModel Objects for Included Relations

[benmarten]

How can I achieve that related Objects that are included (via include filter) are automatically parsed into the correct LBModel?

Example:

    <FSDish {
        name = Pizza;
        orders =     (
                    {
                unitPrice = "2.99";
                userId = 54ca8404f0d971928b50b9c8;
            }
        );
    }>

The orders array should contain FSOrder objects, how to achieve that without manually parsing?
I assume creating an SLContract? Any Examples?