Applying bump map in HLSL to diffuse texture

Question

I have multiple layers on this shader which I am using to blend between to define map regions onto a terrain. I am looking to apply height map textures and normal textures to the diffuse textures being used but I am not sure how I should go about doing this. I have added the option to select a bump map for layer 2 but I am not sure how to apply this. I found the Unity documentation quite confusing regarding this since the set up was very different. Very new to HLSL and shaders, would appreciate any help regarding this.

Properties
{
    _Color ("Color", Color) = (1,1,1,1)
    _MainTex ("Albedo (RGB)", 2D) = "white" {}
    _Glossiness("Smoothness", Range(0,1)) = 0.5
    _Metallic("Metallic", Range(0,1)) = 0.1
    _Smoothness("Smoothness", Range(0, 1)) = 0.1
    _BlendSharpness ("Blend Sharpness", Range(0.06, 4)) = 0.75

[Space(30)]
_Layer1("Layer 1", 2D) = "white" {}
_Layer1Height("Layer 1 Height", Range(0, 20)) = 1

 [Space(20)]
_Layer2("Layer 2", 2D) = "white" {}
_BumpMap("Bump map", 2D) = "bump" {}
_Layer2Height("Layer 2 Height", Range(0, 20)) = 1

 [Space(20)]
_Layer3("Layer 3", 2D) = "white" {}
_Layer3Height("Layer 3 Height", Range(0, 20)) = 1

}

SubShader
{
    Tags { "RenderType"="Opaque" }
    LOD 200

CGPROGRAM
float _Metalness;
float _Smoothness;

UNITY_DECLARE_TEX2D(_MainTex);

float _BaseHeight;
float _BlendSharpness;

UNITY_DECLARE_TEX2D(_Layer1);
float _Layer1Height;

UNITY_DECLARE_TEX2D(_Layer2);
UNITY_DECLARE_TEX2D(_BumpMap);
float _Layer2Height;

UNITY_DECLARE_TEX2D(_Layer3);
float _Layer3Height;


struct Input
{
    float2 uv_MainTex;
    float2 uv_Layer1;

    float2 uv_Layer2;
    float2 uv_BumpMap;

    float2 uv_Layer3;
    float3 worldPos;
};

struct blendingData {
    float height;

    float4 result;
};

blendingData BlendLayer(float4 layer, float layerHeight, blendingData bd)
{
    bd.height = max(0, bd.height - layerHeight);
    float t = min(1, bd.height * _BlendSharpness);
    bd.result = lerp(bd.result, layer, t);

    return bd;
}

void surf (Input IN, inout SurfaceOutputStandard o)
{
    blendingData bdata;
    bdata.height = IN.worldPos.y - _BaseHeight;
    bdata.result = UNITY_SAMPLE_TEX2D(_MainTex, IN.uv_MainTex);
    float4 layer1 = UNITY_SAMPLE_TEX2D(_Layer1, IN.uv_Layer1);
    float4 layer2 = UNITY_SAMPLE_TEX2D(_Layer2, IN.uv_Layer2);
    float4 layer3 = UNITY_SAMPLE_TEX2D(_Layer3, IN.uv_Layer3);

    bdata = BlendLayer(layer1, _Layer1Height, bdata);
    bdata = BlendLayer(layer2, _Layer2Height, bdata);
    bdata = BlendLayer(layer3, _Layer3Height, bdata);

    o.Albedo = bdata.result;
    o.Metallic = _Metallic;
    o.Smoothness = _Smoothness;
}