these lines have an id @server side

BookAStar/BookAStar/Model/Workflow/BillingLine.cs

@@ -6,6 +6,7 @@ namespace BookAStar.Model.Workflow
 {
     public class BillingLine : IBillingLine
     {
+        public long Id { get; set; }
         public string Description { get; set; }
         public TimeSpan Duration { get; set; }
         public int Count { get; set; } = 1;