Custom shader to add bruises to character

Hey all, basically right now I have a character with a bumped/diffuse, and what I’d like to do is overlay a second diffuse with just the bruises. So, I need to have the opacity channel intact on the overlayed texture, the issue I’m having trouble with now… I don’t know much about shaders and unfortunately very crunched for time right now, so I can’t spend much more time trying to figure this out… I’ve managed to write a (very simple) shader which overlays an alpha channel to the base diffuse (for another feature in the game):

Shader "Custom/Cutout" {
    Properties {
        _MainTex ("Texture to blend", 2D) = "white" {}
        _Fade ("Base (RGB) Transparency (A)",2D) = "white" {}
    SubShader {
        Tags { "Queue" = "Transparent" }
        Pass {
            Blend  SrcAlpha OneMinusSrcAlpha
            Lighting On
            SetTexture [_MainTex] 
          Pass {
            Blend One One
            Material {
            Diffuse [_Fade] 
            Lighting On

this lets me cut out the alpha channel, but what I’d like now is to be able to “overlay” this on top of a bumped/diffuse pass, so the cutout of the bruises shows up on top of the base diffuse… Again, I apologize for the uneducated nature of my question, I just don’t have the time left to spend on this, any help is greatly appreciated!

Built this with Strumpy’s Sahder Editor:

Shader "BumpedDiffuseOverlay"
_MainTex("Base (RGB)", 2D) = "white" {}
_BumpMap("Normalmap", 2D) = "bump" {}
_Overlay("Overlay", 2D) = "black" {}



Cull Back
ZWrite On
ZTest LEqual
ColorMask RGBA

#pragma surface surf BlinnPhongEditor  vertex:vert
#pragma target 2.0

sampler2D _MainTex;
sampler2D _BumpMap;
sampler2D _Overlay;

			struct EditorSurfaceOutput {
				half3 Albedo;
				half3 Normal;
				half3 Emission;
				half3 Gloss;
				half Specular;
				half Alpha;
				half4 Custom;
			inline half4 LightingBlinnPhongEditor_PrePass (EditorSurfaceOutput s, half4 light)
half3 spec = light.a * s.Gloss;
half4 c;
c.rgb = (s.Albedo * light.rgb + light.rgb * spec);
c.a = s.Alpha;
return c;


			inline half4 LightingBlinnPhongEditor (EditorSurfaceOutput s, half3 lightDir, half3 viewDir, half atten)
				half3 h = normalize (lightDir + viewDir);
				half diff = max (0, dot ( lightDir, s.Normal ));
				float nh = max (0, dot (s.Normal, h));
				float spec = pow (nh, s.Specular*128.0);
				half4 res;
				res.rgb = _LightColor0.rgb * diff;
				res.w = spec * Luminance (_LightColor0.rgb);
				res *= atten * 2.0;

				return LightingBlinnPhongEditor_PrePass( s, res );
			struct Input {
				float2 uv_MainTex;
float2 uv_Overlay;
float2 uv_BumpMap;


			void vert (inout appdata_full v, out Input o) {
float4 VertexOutputMaster0_0_NoInput = float4(0,0,0,0);
float4 VertexOutputMaster0_1_NoInput = float4(0,0,0,0);
float4 VertexOutputMaster0_2_NoInput = float4(0,0,0,0);
float4 VertexOutputMaster0_3_NoInput = float4(0,0,0,0);


			void surf (Input IN, inout EditorSurfaceOutput o) {
				o.Normal = float3(0.0,0.0,1.0);
				o.Alpha = 1.0;
				o.Albedo = 0.0;
				o.Emission = 0.0;
				o.Gloss = 0.0;
				o.Specular = 0.0;
				o.Custom = 0.0;
float4 Sampled2D0=tex2D(_MainTex,IN.uv_MainTex.xy);
float4 Sampled2D1=tex2D(_Overlay,IN.uv_Overlay.xy);
float4 Lerp0=lerp(Sampled2D0,Sampled2D1,Sampled2D1.aaaa);
float4 Sampled2D2=tex2D(_BumpMap,IN.uv_BumpMap.xy);
float4 UnpackNormal0=float4(UnpackNormal(Sampled2D2).xyz, 1.0);
float4 Master0_2_NoInput = float4(0,0,0,0);
float4 Master0_3_NoInput = float4(0,0,0,0);
float4 Master0_4_NoInput = float4(0,0,0,0);
float4 Master0_5_NoInput = float4(1,1,1,1);
float4 Master0_7_NoInput = float4(0,0,0,0);
float4 Master0_6_NoInput = float4(1,1,1,1);
o.Albedo = Lerp0;
o.Normal = UnpackNormal0;

				o.Normal = normalize(o.Normal);
	Fallback "Diffuse"