x3d blending textures transparent

I want to blend two textures, each with specified opacity, follwing is my imaginary code. (no surprise it won't work)

<appearance>
    <ImageTexture url="texture1.jpg" opacity="0.7"></ImageTexture>
    <ImageTexture url="texture2.jpg" opacity="0.3"></ImageTexture>
</appearance>

Looks like it might have something to do with MultiTexture or BlendMode, but I haven't figure out how it works yet.

I just realize an appearance node can have both texture and material properties at the same time, so the following works perfectly fine to me.

<shape>
  <sphere></sphere>
  <appearance>
    <ImageTexture url="texture1.jpg"></ImageTexture>
  </appearance>
</shape>

<shape>
  <sphere></sphere>
  <appearance>
    <material transparency="0.3"></material>
    <ImageTexture url="texture2.jpg"></ImageTexture>
  </appearance>
</shape>