title: Add new property inside interface object without changing class in typescript dynamically
body: <p>I have a class as below.</p>
  
  <pre><code>export class Cars implements Vehicales {
      color?: string;
      type?: string[];
  }
  </code></pre>
  
  <p>Due to some reason I cannot modify my above export object.
  And the templates object is passed to kendoReactGrid where it contains all the strings for the columns and I need to add it inside my interface only and not the export object.</p>
  
  <p>I have an interface as below</p>
  
  <pre><code>interface CarpProps {
      templates: Cars[]
  }
  </code></pre>
  
  <p>Now I want to add an additional property <code>tyreCount: string[]</code> to my templates object.
  How can i do that in typescript interface?
  I tried during extends keyword but was not successfull.
  I am new to typescript any help would be appreciated.</p>