diff --git a/SysML2.NET.Tests/Extend/ParameterMembershipExtensionsTestFixture.cs b/SysML2.NET.Tests/Extend/ParameterMembershipExtensionsTestFixture.cs
index c35b71c7..519f40bb 100644
--- a/SysML2.NET.Tests/Extend/ParameterMembershipExtensionsTestFixture.cs
+++ b/SysML2.NET.Tests/Extend/ParameterMembershipExtensionsTestFixture.cs
@@ -1,38 +1,93 @@
-// -------------------------------------------------------------------------------------------------
+// -------------------------------------------------------------------------------------------------
 // <copyright file="ParameterMembershipExtensionsTestFixture.cs" company="Starion Group S.A.">
-// 
+//
 //   Copyright 2022-2026 Starion Group S.A.
-// 
+//
 //   Licensed under the Apache License, Version 2.0 (the "License");
 //   you may not use this file except in compliance with the License.
 //   You may obtain a copy of the License at
-// 
+//
 //        http://www.apache.org/licenses/LICENSE-2.0
-// 
+//
 //    Unless required by applicable law or agreed to in writing, software
 //    distributed under the License is distributed on an "AS IS" BASIS,
 //    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 //    See the License for the specific language governing permissions and
 //    limitations under the License.
-// 
+//
 // </copyright>
 // ------------------------------------------------------------------------------------------------
 
 namespace SysML2.NET.Tests.Extend
 {
     using System;
-    
+
     using NUnit.Framework;
-    
+
+    using SysML2.NET.Core.Core.Types;
+    using SysML2.NET.Core.POCO.Core.Features;
+    using SysML2.NET.Core.POCO.Core.Types;
     using SysML2.NET.Core.POCO.Kernel.Behaviors;
+    using SysML2.NET.Core.POCO.Root.Elements;
+    using SysML2.NET.Core.POCO.Root.Namespaces;
+    using SysML2.NET.Exceptions;
+    using SysML2.NET.Extensions;
+
+    using Type = SysML2.NET.Core.POCO.Core.Types.Type;
 
     [TestFixture]
     public class ParameterMembershipExtensionsTestFixture
     {
         [Test]
-        public void ComputeOwnedMemberParameter_ThrowsNotSupportedException()
+        public void VerifyComputeOwnedMemberParameter()
         {
-            Assert.That(() => ((IParameterMembership)null).ComputeOwnedMemberParameter(), Throws.TypeOf<NotSupportedException>());
+            Assert.That(() => ((IParameterMembership)null).ComputeOwnedMemberParameter(), Throws.TypeOf<ArgumentNullException>());
+
+            var parameterMembership = new ParameterMembership();
+
+            Assert.That(() => parameterMembership.ComputeOwnedMemberParameter(), Throws.TypeOf<IncompleteModelException>());
+
+            var owningType = new Type();
+            var feature = new Feature();
+
+            owningType.AssignOwnership(parameterMembership, feature);
+
+            Assert.That(parameterMembership.ComputeOwnedMemberParameter(), Is.SameAs(feature));
+
+            // Wiring two features to verify the multiple-element guard:
+            // First remove the existing wiring so we can create a fresh membership with two elements.
+            var twoElementMembership = new ParameterMembership();
+            var secondFeature = new Feature();
+
+            ((IContainedRelationship)twoElementMembership).OwnedRelatedElement.Add(feature);
+            ((IContainedRelationship)twoElementMembership).OwnedRelatedElement.Add(secondFeature);
+
+            Assert.That(() => twoElementMembership.ComputeOwnedMemberParameter(), Throws.TypeOf<IncompleteModelException>());
+
+            // NOTE: wiring a non-IFeature element as the sole OwnedRelatedElement is not possible via the
+            // public AssignOwnership API (IParameterMembership requires an IFeature target).
+            // To cover the as-cast-returns-null path we directly populate OwnedRelatedElement with a
+            // plain Namespace (which is not an IFeature).
+            var nonFeatureMembership = new ParameterMembership();
+            var nonFeatureElement = new Namespace();
+
+            ((IContainedRelationship)nonFeatureMembership).OwnedRelatedElement.Add(nonFeatureElement);
+
+            Assert.That(nonFeatureMembership.ComputeOwnedMemberParameter(), Is.Null);
+        }
+
+        [Test]
+        public void VerifyComputeParameterDirectionOperation()
+        {
+            Assert.That(() => ((IParameterMembership)null).ComputeParameterDirectionOperation(), Throws.TypeOf<ArgumentNullException>());
+
+            var parameterMembership = new ParameterMembership();
+            var owningType = new Type();
+            var feature = new Feature();
+
+            owningType.AssignOwnership(parameterMembership, feature);
+
+            Assert.That(parameterMembership.ComputeParameterDirectionOperation(), Is.EqualTo(FeatureDirectionKind.In));
         }
     }
 }
diff --git a/SysML2.NET/Extend/ParameterMembershipExtensions.cs b/SysML2.NET/Extend/ParameterMembershipExtensions.cs
index f8c14f20..273b0f22 100644
--- a/SysML2.NET/Extend/ParameterMembershipExtensions.cs
+++ b/SysML2.NET/Extend/ParameterMembershipExtensions.cs
@@ -30,6 +30,7 @@ namespace SysML2.NET.Core.POCO.Kernel.Behaviors
     using SysML2.NET.Core.POCO.Root.Annotations;
     using SysML2.NET.Core.POCO.Root.Elements;
     using SysML2.NET.Core.POCO.Root.Namespaces;
+    using SysML2.NET.Exceptions;
 
     /// <summary>
     /// The <see cref="ParameterMembershipExtensions"/> class provides extensions methods for
@@ -46,10 +47,16 @@ internal static class ParameterMembershipExtensions
         /// <returns>
         /// the computed result
         /// </returns>
-        [System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
         internal static IFeature ComputeOwnedMemberParameter(this IParameterMembership parameterMembershipSubject)
         {
-            throw new NotSupportedException("Create a GitHub issue when this method is required");
+            if (parameterMembershipSubject == null)
+            {
+                throw new ArgumentNullException(nameof(parameterMembershipSubject));
+            }
+
+            return parameterMembershipSubject.OwnedRelatedElement.Count != 1
+                ? throw new IncompleteModelException($"{nameof(parameterMembershipSubject)} must have exactly one related element")
+                : parameterMembershipSubject.OwnedRelatedElement[0] as IFeature;
         }
 
         /// <summary>
@@ -67,10 +74,14 @@ internal static IFeature ComputeOwnedMemberParameter(this IParameterMembership p
         /// <returns>
         /// The expected <see cref="FeatureDirectionKind" />
         /// </returns>
-        [System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
         internal static FeatureDirectionKind ComputeParameterDirectionOperation(this IParameterMembership parameterMembershipSubject)
         {
-            throw new NotSupportedException("Create a GitHub issue when this method is required");
+            if (parameterMembershipSubject == null)
+            {
+                throw new ArgumentNullException(nameof(parameterMembershipSubject));
+            }
+
+            return FeatureDirectionKind.In;
         }
     }
 }