How to gather input dictionary in output?

I've been requested to use Camunda as a data auditing tool. I've built a Decision Table and am using the engine-rest to send values from a table into the DMN. The way I'm using it at the moment is I'm gathering the records from a table as a json and then parsing them to the DMN. Each DMN will have different requirements and input variables but they all should be from the same table so sending more records than needed is accepted. However, I'd like to have an output column that gathers the actual inputs used by the DMN.

Is there a built-in Function that can do that?

For example. I'm sending a dictionary of 100 columns that contains the test1 and test2 columns. I'd like a dynamic outputColumn that could be used on any DMN regardless of the inputs they take and that could return

{
  "ouputColumn" {
    "value": {
      "test1": {{input_val_used_for_test1}},
      "test2": {{input_val_used_for_test2}}
    }
  }
}

After evaluating the DMN we need to be able to check which values were used that triggered these rules.

So far I've been able to achieve this by first using the {{base_url}}/decision-definition/key/{{key}}/xml api then pre-filtering the records to only include these columns. Then I append these values in the backend to the output received from Camunda but I'm hoping there is a built-in function that can achieve this.