How to paint a landscape layer while not removing other layers?

The scenario is like this:

I have three landscape paint layers. The first one is painted with “fill layer” (all). I paint with second one some big area (let’s call: Area1). With third layer, I paint a small area (let’s call: Area2) which is inside the area already painted on second layer. So far so good.

When I clear all third layer with “clear layer”. I was expecting the see the Area2 is is now painted with layer2 material. However I see that it is painted with layer1 material. UE4 seems to not work like photoshop layers. Layers (other than first layer) seem all paint on the same effective layer. Therefore when you paint on a layer other than first layer the other layers are deleted.

The problem is bigger with landscape grass type. If I painted a layer and assigned a grass type to that layer, I would then expect the grass to spawn all over that layer, regardless of however i painted other layers. What it does instead, is that it only spawns in Area1 “exclusively” (meaning Area1 - Area2).

Is there any mode switch in UE4 to work as I expected?

What I tried to aim described in my question can be accomplished by just adding your layer infos in “Non-Weight Blended Layer” mode. For anyone having the same problem in the future. Only hoped documentation was better.