I'm a beginner, so please bear with me. I think there is a simple solution to my question but I can't find it.
I want to use two different textures on my model: a gold texture (that comes with normal, metal, roughness layers etc.) AND a texture I painted on photoshop and applied on a UV map.
SO I want the whole character to have the gold texture, except his eyes and a part of his face. For those, I want the photoshop texture. So on the UV map I colored via photoshop, I colored only the eyes and the part of the face I want with this texture, I left the rest blank.
My goal is to put the photoshop texture on top of the gold layer.
I tried 2 ways: -method 1: I created 2 materials: one for each texture, and set up my nodes. However, what appears on screen is one of the two textures, depending on which material is on top of the other: the empty parts of the photoshop texture don't show the golden texture that should be underneath, it only shows black.
-method 2: I created only 1 material, and used an rgb mix node to connect each texture to a color slot of the rgb ix node. Then I connected that mix to the principled BSDF. This time the photoshop texture is combined with the gold texture, everything is at the right place BUT the "properties" of the golden texture (metallic, roughness...) have been applied to the photoshop layer as well, which I want to avoid. So how can I split the golden texture properties from the photoshop texture?

If you need more pictures or any file to answer the questions, don't hesitate to tell me! It would be awesome to get some help!
EDIT:
Here is a screenshot of what happens if I use a mix shader and plug the alpha channel of my texture image to the factor of the mix shader:



