Hi Tim.

You can achieve this by creating your own UrlProvider and override the URL for nodes of type comment to redirect to its parent. There is a great tutorial on 24days by Jeroen Breuer about creating you own UrlProvider and ContentFinder (but i dont think you need a contentfinder for this scenario): http://24days.in/umbraco/2014/urlprovider-and-contentfinder/

Based on your post and Jeroens tutorial, i think something like this would do the trick for you:

using System;
using System.Collections.Generic;
using System.Linq;
using Umbraco.Core;
using Umbraco.Web;
using Umbraco.Web.Routing;

namespace MyUmbracoApplication
{
    public class CommentUrlProvider : IUrlProvider
    {
        public string GetUrl(UmbracoContext umbracoContext, int id, Uri current, UrlProviderMode mode)
        {
            var content = umbracoContext.ContentCache.GetById(id);
            if (content != null && content.DocumentTypeAlias == "comment" && content.Parent != null)
            {
                return content.Parent.Url; //The comment will be redirected to its parent.
            }

            return null;
        }

        public IEnumerable<string> GetOtherUrls(UmbracoContext umbracoContext, int id, Uri current)
        {
            return Enumerable.Empty<string>();
        }
    }

    public class ApplicationStartUp : ApplicationEventHandler
    {
        protected override void ApplicationStarting(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
        {
            UrlProviderResolver.Current.InsertTypeBefore<DefaultUrlProvider, CommentUrlProvider>();
        }
    }
}

I have´nt tried this together with the Frontend Editing package, but here´s the result for me when i´ve tried to set up a similar backoffice as you with articles and comments. (See animation)

Hope this could be helpful!