<MaterialQuantities>
<Item>2</Item> - 2 materials for the horse
<Item>2</Item> - 2 materials for the rider
</MaterialQuantities>
<MeshNames>
<Item>Horse_meshShape</Item>
<Item>Knight_meshShape</Item>
</MeshNames>
So that's where the crux of the matter lies! In my case, there are actually 4 of them. But the point is clear and the essence has been grasped. Thanks!