diff --git a/protocol/esta/dmx/patch.cpp b/protocol/esta/dmx/patch.cpp
index b23126e..17e3275 100644
--- a/protocol/esta/dmx/patch.cpp
+++ b/protocol/esta/dmx/patch.cpp
@@ -22,6 +22,7 @@
   SOFTWARE.
 */
 
+#include "dmx.h"
 #include "patch.h"
 
 namespace DMX {
@@ -34,4 +35,118 @@ Patch::Patch()
 
 }
 
+
+/**
+ * @brief Add a Device to the patch.
+ * @param dev
+ */
+void Patch::addDevice(const std::shared_ptr<Device> dev)
+{
+  devices_.emplace(dev);
+}
+
+
+/**
+ * @brief Remove a Device from the patch.
+ * @param dev
+ */
+void Patch::remDevice(const std::shared_ptr<Device> dev)
+{
+  for (auto it = devices_.begin(); it != devices_.end();)
+  {
+    if (it->expired())              // purge stale devices
+      it = devices_.erase(it);
+    else if (it->lock() == dev)
+      it = devices_.erase(it);
+    else
+      ++it;
+  }
+}
+
+
+/**
+ * @brief Check if a Device is in the patch.
+ * @param dev
+ * @return
+ */
+bool Patch::hasDevice(const std::shared_ptr<Device> dev)
+{
+  for (auto it = devices_.begin(); it != devices_.end();)
+  {
+    if (it->expired())                      // purge stale devices
+      it = devices_.erase(it);
+    else if (it->lock() == dev)
+      return true;
+    else
+      ++it;
+  }
+  return false;
+}
+
+
+/**
+ * @brief Get the list of patched Devices.
+ * @return
+ */
+const std::set<std::weak_ptr<Device>> * Patch::devices() const
+{
+  return &devices_;
+}
+
+
+/**
+ * @brief Check the patch for device footprint conflicts
+ * @return
+ */
+std::set<std::weak_ptr<Device>> Patch::conflicts()
+{
+  std::set<std::weak_ptr<Device>> bad;
+
+  for (auto it = devices_.begin(); it != devices_.end();)
+  {
+    if (it->expired()) {                    // purge stale devices
+      it = devices_.erase(it);
+      continue;
+    }
+
+    auto dev = it->lock();
+
+    // footprint cannot overlow universe
+    if (dev->address() + dev->footprint() >= E111_LAST_SLOT) {
+      bad.emplace(dev);
+      ++it;
+      continue;
+    }
+
+    // start address cannot overlap the prior device
+    if (it != devices_.begin()) {
+      auto prev = std::prev(it)->lock();
+      if (dev->address() < prev->address() + prev->footprint()) {
+        bad.emplace(dev);
+        ++it;
+        continue;
+      }
+    }
+
+    // footprint cannot overlap the next device
+    auto nextItr = std::next(it);
+    while(true) {
+      if (nextItr == devices_.end())        // device is the last member of the patch
+        break;
+      if (nextItr->expired()) {             // next device is stale, purge it
+        nextItr = devices_.erase(nextItr);
+        continue;
+      }
+      auto next = nextItr->lock();
+      if (dev->address() + dev->footprint() >= next->address())
+        bad.emplace(dev);
+      break;
+    }
+
+    ++it;
+  }
+
+  return bad;
+}
+
 } // namespace DMX
diff --git a/protocol/esta/dmx/patch.h b/protocol/esta/dmx/patch.h
index df266e8..7f870a1 100644
--- a/protocol/esta/dmx/patch.h
+++ b/protocol/esta/dmx/patch.h
@@ -23,6 +23,11 @@
 */
 #pragma once
 
+#include "device.h"
+
+#include <memory>
+#include <set>
+
 namespace DMX {
 
 /**
@@ -32,6 +37,16 @@ class Patch
 {
 public:
   explicit Patch();
+
+  void addDevice(const std::shared_ptr<Device>);
+  void remDevice(const std::shared_ptr<Device>);
+  bool hasDevice(const std::shared_ptr<Device>);
+
+  const std::set<std::weak_ptr<Device>> *devices() const;
+  std::set<std::weak_ptr<Device>> conflicts();
+
+private:
+  std::set<std::weak_ptr<Device>> devices_;
 };
 
 } // namespace DMX