Merge TilemapLayers

[Aquarius]

Hi, i have tilemap with :

4 background layers,

1 collision layer (not rendered),

1special layer (wich is not rendered too) where i extract sprites to place them as real sprite in the game (like cars, barrels), I have posted my code some days ago

 

But what I want to do, is to merge together all the 4 first layers.

What I think doing is to render the 3rd layer on the 4th, then the 2nd, and finally the first.

 

Any ideashow to achieve it ?