Pass values file from sub charts to parent charts

Question

I use ArgoCD, helm and Openshift with gitOps process. I have repository A (parent), with vales.yaml and values-ext.yaml files, which uses dependencies from repository B (subcharts). Repository B also has two files, values.yaml and values-ext.yaml.

How to use valeus-ext.yaml from sub charts in parent charts to fill templates from subcharts/templates/configmap.yaml. By default, only the values.yaml from subcharts is taken to parent charts.

The structure looks like this:

├── charts
│   └── subcharts.tgz 
├── Chart.yaml
├── templates
│   └── another-k8s-objs.yaml
├── values-ext.yaml
└── values.yaml

Chart.yaml file:

apiVersion: v2
name: example-application
version: 0.1.0-dev.1
dependencies: 
- name: subcharts
  version: 0.1.0
  repository: "@stable"

subcharts.tgz file:

subcharts
├── Chart.yaml
├── templates
│   └── configmap.yaml
├── values-ext.yaml
└── values.yaml

I tried to define the path to values-ext.yaml in subcharts in ArgoCD Application:

project: example-application
source:
  repoURL: >-
   https://path-to-repo-A/example-application.git
  path: .
  targetRevision: HEAD
  helm:
    valueFiles:
      - values.yaml
      - charts/subcharts/values-ext.yaml    <---- failed
...

but ArgoCD first checks if all items from valueFiles exist, then downloads sucharts.tgz dependency which it doesn't unpack, so I get the error: charts/subcharts/values-ext.yaml: no such file or directory