Add Existing Series works, UI shows TVDB Name and Path so you can check before adding to DB.

NzbDrone.Web/Models/AddNewSeriesModel.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.ComponentModel.DataAnnotations;
+using System.Linq;
+using System.Web;
+
+namespace NzbDrone.Web.Models
+{
+    public class AddNewSeriesModel
+    {
+        [Required(ErrorMessage = "Please enter a series name")]
+        [DataType(DataType.Text)]
+        [DisplayName("Single Series Path")]
+        [DisplayFormat(ConvertEmptyStringToNull = false)]
+        public string SeriesName { get; set; }
+    }
+}