Common attribute for multiple schema files in BPMN (xml)

Question

Can someone help me with a way to add a common attribute to multiple flow schemas?

I have different schema files for different task types which are responsible for attributes of those tasks. I want to add a common attribute to all the schemas, but if I do so I get the error mentioned in image.

Schema file:

{
  "name": "voice",
  "uri": "http://some-company/schema/bpmn/ivr",
  "$schema": "http://json-schema.org/draft-07/schema",
  "description": "Properties for the voice file",
  "prefix": "voice",
  "xml": {
    "tagAlias": "lowerCase"
  },
  "types": [
    {
      "name": "voiceFile",
      "extends": [
        "bpmn:Task"
      ],
      "properties": [
        {
          "name": "taskType",
          "description": "This variable tells what type of task it is",
          "isAttr": true,
          "type": "String"
        },
        {
          "name": "taskName",
          "description": "hold task's name",
          "isAttr": true,
          "type": "String"
        },
        {
          "name": "isDisabledVoice",
          "isAttr": false,
          "description": "tells if the element is disabled",
          "type": "String"
        }
      ]
    }
  ],
  "emumerations": [],
  "associations": []
}

I tried adding attributes from frontend by:

const modeler = ModelerService.getModeler();
const modeling = modeler.get('modeling');
const attrInfo = {};
attrInfo[key] = value;
modeling.updateProperties(el, attrInfo);

Here, key is the attribute name and value is the attribute value.

This should have normally added the attribute to the xml tags, but when I add the attribute to more than one type of tasks, then it gives conflict that same attribute can not be added to more than one task.

Method-2: I have also tried using $ref attribute of json-schema: Base schema:

    {
    "$id": "/schemas/base",
    "$schema": "http://json-schema.org/draft-07/schema",
    "type": "object",
    "properties": {
      "disabled": {
        "type": "boolean",
        "description": "Indicates if the element is disabled"
      }
    }
}

and in the child schema where I need to use the properties mentioned in base schema:

{

  "name": "interactiveVoice",
  "uri": "http://some-company/schema/bpmn/ivr",
  "$schema": "http://json-schema.org/draft-07/schema",
  "description": "Properties for the voice file",
  "prefix": "voice",
  "xml": {
    "tagAlias": "lowerCase"
  },
  "allOf": [
    {"$ref": "./base.schema.json"},
    {
      "type": "object",
      "properties": {
        "taskType": {
          "description": "This variable tells what type of task it is",
          "isAttr": true,
          "type": "string"
        },
        "taskName": {
          "description": "hold task's name",
          "isAttr": true,
          "type": "string"
        },
        "isTTS": {
          "description": "tells that is this voice file is uploaded or generated via tts",
          "isAttr": true,
          "type": "boolean"
        },
        "voiceFileInfo": {
          "description": "hold the infomation related to voice file - voice file name, path, type",
          "isAttr": true,
          "type": "object"
        }
      }
    }
  ],
  "types": [
    {
      "name": "voiceFilePlayerTask",
      "extends": [
        "bpmn:Task"
      ]
    }
  ],
  "emumerations": [],
  "associations": []
}

But still it gives error, and the properties are not being inherited. When I am using the other schema in which base schema is used with $ref, it does not gives us access to the attribute present in the base schema. Why is that so? Any help would be greatly appreciated.