How to mix 2 textures using different UV maps on one object

Question

I have a model: tree with few branches. The main tree trunk is laid on one UV map, and all branches laid on the second uv map. I have a textures ready for both of them, but i'm having trouble mixing them.

Here is a little picture to illustrate:

I want to mix those 2 textures and see them both on the same object. I have tried using "Mix Shader", and it works, but it only lets me see one of my textures at a time. Or if i put mix slider on 0.5, i can see both of them half muted. I also tried using "Add Shader" to mix my textures, and for some reason it produces something that also looks like a half muted combination of my 2 textures. And i would like to see them both simultaneously at the full power.

I also have searched the solution, but was unable to find anything that handled my situation. All tutorials that i found handled the case where few UV sets was identical and textures was laid on each other just by using "Factor" attribute. In my case UV are radically different and textures do not lay on each other, so i was unable to use anything i learned from those tutorials i found.

Answer 1

I figured things out. I don't really understand why it works, but i was able to resolve my problem by inputting alpha of one of the textures into "Mix shader" factor.

This is a easy stuff, but i didn't expect it to work, because my UV sets are very different, and if merged together will interpenetrate each other and create a mess, so i didn't consider doing alpha of one of my textures as a mask.