Combine two normal maps and control the strength of each I use this node setup to combine my two normal maps.


I adapted this method from here.

How to Combine two Normal Maps?

It works perfectly to just combine the maps.
But now i need individual contol over the strength each of them. 

Is there a way to do this ?
A more precise result can be found using these formulas...
Here's an adaptation of it including a Factor value for mixing:


some more details can be found in this thread in BA

And the nodegroup can be found here.