Dynamic scope in Autoform pushArray (attach reply into specified commentId)

I have singlePost with postId. In each singlePost, I list comment.

Autoform for comment:

  {{#autoForm id="updateCommentArray" type="update-pushArray" collection=Collections.Posts doc=commentDoc scope="comment" template="semanticUI"}}
    {{> afQuickField name="content"}}
    <div class="form-group">
      <button type="submit" class="ui positive button">Submit</button>
      <button type="reset" class="ui negative button">Reset</button>

What Autoform provide is to use scope to attach new array into specified field. For example, when I use scope comment.0.reply, that reply will attach to first array of comment. When I use scope comment.1.reply, that reply will attach to second array of comment. Etc

How to make it dynamic? What I thought is to use commentId, but how?

Thank you