In a helm chart, I want to access one of the dependencies’ values in my parent chart.

apiVersion: v2
name: hajhosein-kube-prom
description: A Helm chart for Kubernetes

# The version of the parent chart
version: 0.1.0

# The version of Helm required to use this chart
appVersion: "1.16.0"

# Add the kube-prometheus-stack chart as a dependency
dependencies:
  - name: kube-prometheus-stack
    version: "61.3.1"
    repository: "https://prometheus-community.github.io/helm-charts"

And my values.yaml file is something like this:

kube-prometheus-stack:
  prometheus:
    thanosService:
      enabled: false

  thanosRuler:
    enabled: false
prometheus:
  thanosService:
    enabled: true
...

In my parent templates I want to use a file from the dependency and change some of its properties(they can not be changed by modifying values). I have copied this file to templates/prometheus/ path of my chart’s root.
When running helm template --dry-run hajoveis-chart ./ I get this:

Error: template: hajhosein-kube-prom/templates/prometheus/serviceThanosSidecar.yaml:20:14: executing "hajhosein-kube-prom/templates/prometheus/serviceThanosSidecar.yaml" at <.Values.prometheus.thanosService.ipDualStack.enabled>: nil pointer evaluating interface {}.enabled

These values are generated in the dependency’s template. I want to somehow access them in my current chart.