Standard way of storing and retrieving custom xml in android?

I am working on a 3D game in android. I want to create custom themes for my game(for 3D part). My assets(3d models/drawables/sounds) will load as per currently selected theme. However, I want to make these themes based on XML files.

my xml file structure will be something like this

<Theme1>
  <3D Model 1> // from res/raw
  <3D Model 2> // from res/raw
  <3D Model 3> // from res/raw  
  <Multiple Drawables> // from /res/drawable
  <Some sounds> // from res/raw
</Theme1>
<Theme2>
.
.
</Theme2>
.
.

I am not sure how should i do it in best possible way. Please suggest !