Hi Ciaran and welcome you our.

First you need to find the partial view that renders the related post. This partial view is located in here \Views\Partials\uBlogsy\Post\uBlogsyPostListRelatedPosts.cshtml. When you in this file you need to add .OrderBy to the foreach loop so your code look like this.

<aside class="uBlogsy_related_posts_container uBlogsy_bottom_border uBlogsy_font_style20">
     <h3>@library.GetDictionaryItem("uBlogsyDicPostsRelated")</h3>
        <ul class="uBlogsy_related uBlogsy_font_style20">
            @foreach (var n in nodes.OrderBy("uBlogsyPostDate desc")){
                <li><a href="@n.Url()" title="@n.GetPropertyValue("uBlogsyContentTitle")"><span>@n.GetPropertyValue("uBlogsyContentTitle")</span>
                    </a>- <span class="uBlogsy_post_date">@(n.GetPropertyValue<DateTime>("uBlogsyPostDate").ToString("d MMMM yyyy"))</span>
                </li>
            }
        </ul>
</aside>

Hope this helps,

/Dennis