Photoshop :: Blend If Inside Groups Or Smart

I resized it to fit the background notepad and made several identical copies of the texture layer, their only difference being different values for "blend if underlying layer", so that the texture smoothly ends with the underlying notepad on each side (as there are luminosity differences both on the notepad and the notepads background).

That looks fine for "normal blending" (dont worry about the messy bottom, it will be cropped when everythings done). But I actually need the texture to be multiplied with the background layer. Obviously setting each layer to multiply isnt going to cut it because they would multiply each other, too. So I need to either put all the layers into a smart object (option 1) or option 2, which Ill resort to here put all layers into a group set to multiply, since this way all of the layers in the group are put together first and the composite group is then treated as a single image and blended with the rest of the image, using multiply.

... whereas I rather expected the result to look like this (I only roughly masked the edges for demonstration purposes):

To me it seems, as if putting the group would nullify the "blend if underlying layer" settings for each layer. Besides, the same happens if I use a smart object instead of the group (option 1). I dont see why this should happen at all.

So my questions: Is this behaviour deliberate? And if so, can somebody explain ?

a solution to get to the last screenshot (without masking manually obviously) ?