diff --git a/source/Octopus.Client.Tests/Operations/RegisterKubernetesClusterOperationFixture.cs b/source/Octopus.Client.Tests/Operations/RegisterKubernetesClusterOperationFixture.cs
index e2550c16d..c98ea0bfe 100644
--- a/source/Octopus.Client.Tests/Operations/RegisterKubernetesClusterOperationFixture.cs
+++ b/source/Octopus.Client.Tests/Operations/RegisterKubernetesClusterOperationFixture.cs
@@ -1,10 +1,12 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using FluentAssertions;
 using NSubstitute;
 using NUnit.Framework;
+using Octopus.Client.Exceptions;
 using Octopus.Client.Extensibility;
 using Octopus.Client.Model;
 using Octopus.Client.Model.Endpoints;
@@ -22,6 +24,7 @@ public class RegisterKubernetesClusterOperationFixture
         ResourceCollection<EnvironmentResource> environments;
         ResourceCollection<MachineResource> machines;
         ResourceCollection<MachinePolicyResource> machinePolicies;
+        private ResourceCollection<ProxyResource> proxies;
 
         [SetUp]
         public void SetUp()
@@ -32,6 +35,7 @@ public void SetUp()
             operation = new RegisterKubernetesClusterOperation(clientFactory);
             serverEndpoint = new OctopusServerEndpoint("http://octopus", "ABC123");
 
+            proxies = new ResourceCollection<ProxyResource>(new ProxyResource[0], LinkCollection.Self("/foo"));
             environments = new ResourceCollection<EnvironmentResource>(new EnvironmentResource[0], LinkCollection.Self("/foo"));
             machines = new ResourceCollection<MachineResource>(new MachineResource[0], LinkCollection.Self("/foo"));
             machinePolicies = new ResourceCollection<MachinePolicyResource>(new MachinePolicyResource[0], LinkCollection.Self("/foo"));
@@ -45,6 +49,7 @@ public void SetUp()
                     .Add("MachinePolicies", "/api/machinepolicies")
                     .Add("CurrentUser", "/api/users/me")
                     .Add("SpaceHome", "/api/spaces")
+                    .Add("Proxies", "/api/proxies")
             };
 
             client.Get<RootResource>(Arg.Any<string>(), Arg.Any<CancellationToken>()).Returns(rootDocument);
@@ -57,6 +62,8 @@ public void SetUp()
                 .Do(ci => ci.Arg<Func<ResourceCollection<MachineResource>, bool>>()(machines));
             client.When(x => x.Paginate(Arg.Any<string>(), Arg.Any<object>(), Arg.Any<Func<ResourceCollection<MachinePolicyResource>, bool>>(), Arg.Any<CancellationToken>()))
                 .Do(ci => ci.Arg<Func<ResourceCollection<MachinePolicyResource>, bool>>()(machinePolicies));
+            client.When(x => x.Paginate(Arg.Any<string>(), Arg.Any<object>(), Arg.Any<Func<ResourceCollection<ProxyResource>, bool>>(), Arg.Any<CancellationToken>()))
+                .Do(ci => ci.Arg<Func<ResourceCollection<ProxyResource>, bool>>()(proxies));
         }
 
         [Test]
@@ -101,5 +108,147 @@ public async Task ShouldCreateNewPollingKubernetesTentacle()
 
             machineResources.Should().ContainSingle().Which.Endpoint.Should().BeOfType<KubernetesTentacleEndpointResource>().Which.Should().BeEquivalentTo(new KubernetesTentacleEndpointResource(new PollingTentacleEndpointConfigurationResource("ABCDEF", "poll://ckyhfyfkcbmzjl8sfgch/")));
         }
+
+        [Test]
+        public async Task ShouldOnlyUpdateEndpointConnectionConfigurationOnExistingMachine()
+        {
+            var updatedMachines = new List<MachineResource>();
+            await client.Update("/machines/whatever/1", Arg.Do<MachineResource>(m => updatedMachines.Add(m)), Arg.Any<object>(), Arg.Any<CancellationToken>());
+
+            environments.Items.Add(new EnvironmentResource {Id = "environments-1", Name = "UAT", Links = LinkCollection.Self("/api/environments/environments-1").Add("Machines", "/api/environments/environments-1/machines")});
+            environments.Items.Add(new EnvironmentResource {Id = "environments-2", Name = "Production", Links = LinkCollection.Self("/api/environments/environments-2").Add("Machines", "/api/environments/environments-2/machines")});
+
+            machines.Items.Add(new MachineResource
+            {
+                Id = "machines/84", EnvironmentIds = new ReferenceCollection(new[] { "environments-1" }), Name = "Mymachine", Links = LinkCollection.Self("/machines/whatever/1"),
+                Endpoint = new KubernetesTentacleEndpointResource(new ListeningTentacleEndpointConfigurationResource("123456", "myMachine.test.com") { ProxyId = "proxy-2" })
+            });
+
+            proxies.Items.Add(new ProxyResource { Id = "proxy-1", Name = "MyNewProxy", Links = LinkCollection.Self("/api/proxies/proxy-1") });
+
+            operation.MachineName = "Mymachine";
+            operation.TentaclePort = 10930;
+            operation.TentacleThumbprint = "ABCDEF";
+            operation.TentacleHostname = "my-new-machine.test.com";
+            operation.CommunicationStyle = CommunicationStyle.TentaclePassive;
+            operation.EnvironmentNames = new[] {"Production"};
+            operation.ProxyName = "MyNewProxy";
+
+            await operation.ExecuteAsync(serverEndpoint).ConfigureAwait(false);
+
+            var thing = updatedMachines.Should().ContainSingle().Which;
+
+            thing.Should().BeEquivalentTo(new MachineResource
+            {
+                Id = "machines/84",
+                Name = "Mymachine",
+                EnvironmentIds = new ReferenceCollection("environments-1"),
+                Endpoint = new KubernetesTentacleEndpointResource(new ListeningTentacleEndpointConfigurationResource("ABCDEF", "https://my-new-machine.test.com:10930/") {ProxyId = "proxy-1"}),
+                Links = LinkCollection.Self("/machines/whatever/1")
+            }, cfg => cfg.RespectingRuntimeTypes());
+        }
+
+        [Test]
+        public async Task ShouldUpdateExistingMachineWhenForceIsEnabled()
+        {
+            environments.Items.Add(new EnvironmentResource {Id = "environments-1", Name = "UAT", Links = LinkCollection.Self("/api/environments/environments-1").Add("Machines", "/api/environments/environments-1/machines")});
+            environments.Items.Add(new EnvironmentResource {Id = "environments-2", Name = "Production", Links = LinkCollection.Self("/api/environments/environments-2").Add("Machines", "/api/environments/environments-2/machines")});
+
+            machines.Items.Add(new MachineResource {Id = "machines/84", EnvironmentIds = new ReferenceCollection(new[] {"environments-1"}), Name = "Mymachine", Links = LinkCollection.Self("/machines/whatever/1")});
+
+            operation.TentacleThumbprint = "ABCDEF";
+            operation.TentaclePort = 10930;
+            operation.MachineName = "Mymachine";
+            operation.TentacleHostname = "Mymachine.test.com";
+            operation.CommunicationStyle = CommunicationStyle.TentaclePassive;
+            operation.EnvironmentNames = new[] {"Production"};
+            operation.AllowOverwrite = true;
+
+            await operation.ExecuteAsync(serverEndpoint).ConfigureAwait(false);
+
+            await client.Received().Update("/machines/whatever/1", Arg.Is<MachineResource>(m =>
+                m.Id == "machines/84"
+                && m.Name == "Mymachine"
+                && m.EnvironmentIds.First() == "environments-2"),
+                Arg.Any<object>(), Arg.Any<CancellationToken>()).ConfigureAwait(false);
+        }
+
+        [Test]
+        public async Task ShouldCreateWhenCantDeserializeMachines()
+        {
+            client.When(x => x.Paginate(Arg.Any<string>(), Arg.Any<object>(), Arg.Any<Func<ResourceCollection<MachineResource>, bool>>()))
+                .Throw(new OctopusDeserializationException(1, "Can not deserialize"));
+
+            environments.Items.Add(new EnvironmentResource { Id = "environments-1", Name = "UAT", Links = LinkCollection.Self("/api/environments/environments-1").Add("Machines", "/api/environments/environments-1/machines") });
+            environments.Items.Add(new EnvironmentResource { Id = "environments-2", Name = "Production", Links = LinkCollection.Self("/api/environments/environments-2").Add("Machines", "/api/environments/environments-2/machines") });
+
+            operation.TentacleThumbprint = "ABCDEF";
+            operation.TentaclePort = 10930;
+            operation.MachineName = "Mymachine";
+            operation.TentacleHostname = "Mymachine.test.com";
+            operation.CommunicationStyle = CommunicationStyle.TentaclePassive;
+            operation.EnvironmentNames = new[] { "Production" };
+
+            await operation.ExecuteAsync(serverEndpoint).ConfigureAwait(false);
+
+            await client.Received().Create("/api/machines", Arg.Is<MachineResource>(m =>
+                m.Name == "Mymachine"
+                && ((KubernetesTentacleEndpointResource)m.Endpoint).TentacleEndpointConfiguration.Uri == "https://mymachine.test.com:10930/"
+                && m.EnvironmentIds.First() == "environments-2"),
+                Arg.Any<object>(), Arg.Any<CancellationToken>()).ConfigureAwait(false);
+        }
+
+        [Test]
+        public async Task ShouldNotOverwriteMachinePolicyToNull()
+        {
+            environments.Items.Add(new EnvironmentResource { Id = "environments-1", Name = "UAT", Links = LinkCollection.Self("/api/environments/environments-1").Add("Machines", "/api/environments/environments-1/machines") });
+            environments.Items.Add(new EnvironmentResource { Id = "environments-2", Name = "Production", Links = LinkCollection.Self("/api/environments/environments-2").Add("Machines", "/api/environments/environments-2/machines") });
+
+            machines.Items.Add(new MachineResource { Id = "machines/84", MachinePolicyId = "MachinePolicies-1", EnvironmentIds = new ReferenceCollection(new[] { "environments-1" }), Name = "Mymachine", Links = LinkCollection.Self("/machines/whatever/1") });
+
+            operation.TentacleThumbprint = "ABCDEF";
+            operation.TentaclePort = 10930;
+            operation.MachineName = "Mymachine";
+            operation.TentacleHostname = "Mymachine.test.com";
+            operation.CommunicationStyle = CommunicationStyle.TentaclePassive;
+            operation.EnvironmentNames = new[] { "Production" };
+            operation.AllowOverwrite = true;
+
+            await operation.ExecuteAsync(serverEndpoint).ConfigureAwait(false);
+
+            await client.Received().Update("/machines/whatever/1", Arg.Is<MachineResource>(m =>
+                m.Id == "machines/84"
+                && m.Name == "Mymachine"
+                && m.EnvironmentIds.First() == "environments-2"
+                && m.MachinePolicyId == "MachinePolicies-1"),
+                Arg.Any<object>(), Arg.Any<CancellationToken>()).ConfigureAwait(false);
+        }
+
+        [Test]
+        public async Task ShouldOverwriteMachinePolicyWhenPassed()
+        {
+            environments.Items.Add(new EnvironmentResource { Id = "environments-1", Name = "UAT", Links = LinkCollection.Self("/api/environments/environments-1").Add("Machines", "/api/environments/environments-1/machines") });
+            environments.Items.Add(new EnvironmentResource { Id = "environments-2", Name = "Production", Links = LinkCollection.Self("/api/environments/environments-2").Add("Machines", "/api/environments/environments-2/machines") });
+
+            machines.Items.Add(new MachineResource { Id = "machines/84", MachinePolicyId = "MachinePolicies-1", EnvironmentIds = new ReferenceCollection(new[] { "environments-1" }), Name = "Mymachine", Links = LinkCollection.Self("/machines/whatever/1") });
+            machinePolicies.Items.Add(new MachinePolicyResource {Id = "MachinePolicies-2", Name = "Machine Policy 2"});
+            operation.TentacleThumbprint = "ABCDEF";
+            operation.TentaclePort = 10930;
+            operation.MachineName = "Mymachine";
+            operation.TentacleHostname = "Mymachine.test.com";
+            operation.CommunicationStyle = CommunicationStyle.TentaclePassive;
+            operation.EnvironmentNames = new[] { "Production" };
+            operation.AllowOverwrite = true;
+            operation.MachinePolicy = "Machine Policy 2";
+
+            await operation.ExecuteAsync(serverEndpoint).ConfigureAwait(false);
+
+            await client.Received().Update("/machines/whatever/1", Arg.Is<MachineResource>(m =>
+                m.Id == "machines/84"
+                && m.Name == "Mymachine"
+                && m.EnvironmentIds.First() == "environments-2"
+                && m.MachinePolicyId == "MachinePolicies-2"),
+                Arg.Any<object>(), Arg.Any<CancellationToken>()).ConfigureAwait(false);
+        }
     }
 }
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