Processor order of operations

Hai all! So as the pictures show, I want to make it so that my structure doesn't spawn ores on it's outside. I tried moving the processors around but the result is bad either way. So basically as a work around I put sandstone where the ores should spawn and then the processor replaces the sandstone with ores and then it should replace the rest of the sandstone with stone. But for some reason no matter what I do it doesn't work. If I make the outside layer sandstone and I want to replace it with just stone, the ores appear on the outside, even if my ore generator processor is the first. If the inside is sandstone, no ores generate what so ever.