Blending mode for roughness or height maps

[a.bezalel]

Hey I am breaking my head here trying to solve this.

I have two fill layers only for the roughness, one using a Crease alpha map
and below that another fill layer (only for roughness as well) with a noise alpha map.

I want to combine the two, BUT no matter what blending mode I use
the upper layer (the one with the crease alpha map) cancel the lower roughness map.

I tried with normal layers, fill layers everything.
I don't want to use a mask, because I want to add the both in a uniform even way.

any help?

-EDIT-
Also while I am at it, why every time a put an alpha mask, in lets say the roughness slot of a fill layer,
if i want to change it, I have to remove it, than it will add back all the other slots (ie height, color, and metal)
and I will have to add a new map to the eoughness and remove the other slots AGAIN?
Why can't I just change the map? the slot turns into a material thing and all the alpha textures are gone from the available selections.

thanks

[Maak]

I'm having the same problem. 

I have a detailed specular map on one layer and on the layer above I have a fill.  The fill layer cancels out the lower layer.  I cannot blend the two. 

I have tried opacity, and different blending modes.  Nothing seems to change it.  The full layer is either 100% on or off.     

[Maak]

Hmm,  I ended up getting it to work. 

It was unresponsive when I changed blending modes the first time.  But when I switched to a different channel and then back to the original channel it behaves as expected and the blending modes worked.