diff --git a/Mongo_Engine/Convert/MongoQuery.cs b/Mongo_Engine/Convert/MongoQuery.cs
index 678a228..fdf2974 100644
--- a/Mongo_Engine/Convert/MongoQuery.cs
+++ b/Mongo_Engine/Convert/MongoQuery.cs
@@ -20,9 +20,13 @@
  * along with this code. If not, see <https://www.gnu.org/licenses/lgpl-3.0.html>.      
  */
 
+using BH.Engine.Reflection;
+using BH.oM.Base.Attributes;
 using BH.oM.Data.Requests;
 using MongoDB.Bson;
+using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Linq;
 
 namespace BH.Engine.Adapters.Mongo
@@ -30,9 +34,12 @@ namespace BH.Engine.Adapters.Mongo
     public static partial class Convert
     {
         /***************************************************/
-        /**** Public Interface                           ****/
+        /**** Public Interface                          ****/
         /***************************************************/
 
+        [Description("Converts a given IRequest into Bson document.")]
+        [Input("query", "Request to be converted to a Bson document.")]
+        [Output("document", "Bson document that resulted from converting the input request.")]
         public static BsonDocument IToMongoQuery(this IRequest query)
         {
             return ToMongoQuery(query as dynamic);
@@ -40,9 +47,12 @@ public static BsonDocument IToMongoQuery(this IRequest query)
 
 
         /***************************************************/
-        /**** Private  Methods - Curves                 ****/
+        /**** Public Methods                            ****/
         /***************************************************/
 
+        [Description("Converts a given CustomRequest into Bson document.")]
+        [Input("query", "Request to be converted to a Bson document.")]
+        [Output("document", "Bson document that resulted from converting the input request.")]
         public static BsonDocument ToMongoQuery(this CustomRequest query)
         {
             return BsonDocument.Parse(query.Body);
@@ -50,6 +60,9 @@ public static BsonDocument ToMongoQuery(this CustomRequest query)
 
         /***************************************************/
 
+        [Description("Converts a given FilterRequest into Bson document.")]
+        [Input("query", "Request to be converted to a Bson document.")]
+        [Output("document", "Bson document that resulted from converting the input request.")]
         public static BsonDocument ToMongoQuery(this FilterRequest query)
         {
             BsonDocument document = new BsonDocument();
@@ -57,10 +70,26 @@ public static BsonDocument ToMongoQuery(this FilterRequest query)
             // Define the match
             if (query.Equalities == null)
                 query.Equalities = new Dictionary<string, object>();
+
             BsonDocument equalities = query.Equalities.ToBsonDocument();
 
             if (query.Type != null)
-                equalities["_t"] = query.Type.ToString();
+            {
+                BsonArray typeEqualities = new BsonArray();
+
+                // Add requested type if it is not an interface
+                if (!query.Type.IsInterface)
+                    typeEqualities.Add(new BsonDocument { { "_t", query.Type.ToString() } });
+
+                // Add subtypes of the requested type
+                foreach (Type subtype in query.Type.Subtypes())
+                {
+                    typeEqualities.Add(new BsonDocument { { "_t", subtype.ToString() } });
+                }
+
+                equalities.Add(new BsonElement("$or", typeEqualities));
+            }
+
             if (query.Tag != "")
                 equalities["__Tag__"] = query.Tag;
 
@@ -71,6 +100,9 @@ public static BsonDocument ToMongoQuery(this FilterRequest query)
 
         /***************************************************/
 
+        [Description("Converts a given IResultRequest into Bson document.")]
+        [Input("query", "Request to be converted to a Bson document.")]
+        [Output("document", "Bson document that resulted from converting the input request.")]
         public static BsonDocument ToMongoQuery(this IResultRequest query)
         {
             BsonDocument document = new BsonDocument();
@@ -97,6 +129,8 @@ public static BsonDocument ToMongoQuery(this IResultRequest query)
         }
 
 
+        /***************************************************/
+        /**** Fallback Methods                          ****/
         /***************************************************/
 
         private static BsonDocument ToMongoQuery(this IRequest query)
diff --git a/Mongo_Engine/Mongo_Engine.csproj b/Mongo_Engine/Mongo_Engine.csproj
index 08315ed..4665326 100644
--- a/Mongo_Engine/Mongo_Engine.csproj
+++ b/Mongo_Engine/Mongo_Engine.csproj
@@ -3,7 +3,7 @@
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
     <AssemblyVersion>6.0.0.0</AssemblyVersion>
-            <Description>https://github.com/BHoM/Mongo_Toolkit</Description>
+    <Description>https://github.com/BHoM/Mongo_Toolkit</Description>
     <Version>5.0.0</Version>
     <Authors>BHoM</Authors>
     <Copyright>Copyright © https://github.com/BHoM</Copyright>
@@ -41,6 +41,11 @@
       <HintPath>C:\ProgramData\BHoM\Assemblies\Data_oM.dll</HintPath>
       <Private>False</Private>
     </Reference>
+    <Reference Include="Reflection_Engine">
+      <HintPath>C:\ProgramData\BHoM\Assemblies\Reflection_Engine.dll</HintPath>
+      <SpecificVersion>False</SpecificVersion>
+      <Private>False</Private>
+    </Reference>
     <Reference Include="Serialiser_Engine">
       <SpecificVersion>False</SpecificVersion>
       <HintPath>C:\ProgramData\BHoM\Assemblies\Serialiser_Engine.dll</HintPath>