Haven't tried decal applications yet. I have to look into how to do it. Would be helpful.

Easy. Find the texture on the brick wall in the file it's in. Upload that into photoshop or gimp. Then I would take a png image, I usually render a png picture to make like a painting, and then upload that png into the photoshop or gimp. Then layer the png over the brick texture. Adjust the translucency of the png to make the brick show through it. Then export that picture into the where you got the texture image and then in daz or whatever, apply the new texture you made to the wall. It might take a few tries but that's the basic process. Or you can make a plane have an png image, but you'll have to also make a ocupacy white photo of the same picture. That way the png dont appear with a white background around the image. Then just align the plane with the wall. I used the first method on my old world entry, and the second method on my frog entry. Both work well to achieve Graffiti texture application.