How: dashbard with two data sources

I have single CloudWatch datasource and multiple data sources for Prometheus - one per cluster. Now I am trying to mix two dashboards: 5984 (Linux Nodes Disk Usage only) and 617. If I add:

  "__inputs": [
        "name": "DS_PROMETHEUS",
        "label": "Prometheus",
        "description": "",
        "type": "datasource",
        "pluginId": "prometheus",
        "pluginName": "Prometheus"

on the top of the json file it is always asking for data source for specific k8s cluster and displays disk usage panel including all nodes in it and it is not linked to other variables (instanceid, region, etc.) So if I change the CloudWatch AWS region it always stays the same. How can I add all Prometheus data sources to Datasource dropdown menu?

I have tried to add prometheus to query in:

  "templating": {
    "list": [
        "current": {},
        "hide": 0,
        "includeAll": false,
        "label": "Datasource",
        "multi": false,
        "name": "datasource",
        "options": [],
        "query": "cloudwatch",
        "refresh": 1,
        "regex": "",
        "skipUrlSync": false,
        "type": "datasource"

but that didn’t work. This is my mixed json file: