diff --git a/php-classes/Slate/CBL/Demonstrations/DidNotMeetDemonstrationSkill.php b/php-classes/Slate/CBL/Demonstrations/DidNotMeetDemonstrationSkill.php
new file mode 100644
index 000000000..f9c985408
--- /dev/null
+++ b/php-classes/Slate/CBL/Demonstrations/DidNotMeetDemonstrationSkill.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Slate\CBL\Demonstrations;
+
+
+class DidNotMeetDemonstrationSkill extends DemonstrationSkill
+{
+
+}
\ No newline at end of file
diff --git a/php-classes/Slate/CBL/Demonstrations/MissingDemonstrationSkill.php b/php-classes/Slate/CBL/Demonstrations/MissingDemonstrationSkill.php
new file mode 100644
index 000000000..e2974f63a
--- /dev/null
+++ b/php-classes/Slate/CBL/Demonstrations/MissingDemonstrationSkill.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Slate\CBL\Demonstrations;
+
+
+class MissingDemonstrationSkill extends DemonstrationSkill
+{
+
+}
\ No newline at end of file
diff --git a/php-migrations/Slate/CBL/Demonstrations/20210328_demoskill-subclass-dnm.php b/php-migrations/Slate/CBL/Demonstrations/20210328_demoskill-subclass-dnm.php
new file mode 100644
index 000000000..35c032a9d
--- /dev/null
+++ b/php-migrations/Slate/CBL/Demonstrations/20210328_demoskill-subclass-dnm.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace Slate\CBL\Demonstrations;
+
+
+$tableName = DemonstrationSkill::$tableName;
+$historyTableName = DemonstrationSkill::getHistoryTableName();
+
+// skip if table doesn't exist
+if (!static::tableExists($tableName)) {
+    printf("Skipping migration because table `%s` does not yet exist\n", $tableName);
+    return static::STATUS_SKIPPED;
+}
+
+// skip if Class column already contains DidNotMeet subclass
+if (static::hasColumnEnumValue($tableName, 'Class', DidNotMeetDemonstrationSkill::class)) {
+    printf("Skipping migration because column `%s`.`Class` already has value '%s'\n", $tableName, DidNotMeetDemonstrationSkill::class);
+    return static::STATUS_SKIPPED;
+}
+
+// add new Class value
+static::addColumnEnumValue($tableName, 'Class', DidNotMeetDemonstrationSkill::class);
+static::addColumnEnumValue($historyTableName, 'Class', DidNotMeetDemonstrationSkill::class);
diff --git a/php-migrations/Slate/CBL/Demonstrations/20210328_demoskill-subclass-missing.php b/php-migrations/Slate/CBL/Demonstrations/20210328_demoskill-subclass-missing.php
new file mode 100644
index 000000000..a68cb7d68
--- /dev/null
+++ b/php-migrations/Slate/CBL/Demonstrations/20210328_demoskill-subclass-missing.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace Slate\CBL\Demonstrations;
+
+use DB;
+
+
+$tableName = DemonstrationSkill::$tableName;
+$historyTableName = DemonstrationSkill::getHistoryTableName();
+
+// skip if table doesn't exist
+if (!static::tableExists($tableName)) {
+    printf("Skipping migration because table `%s` does not yet exist\n", $tableName);
+    return static::STATUS_SKIPPED;
+}
+
+// skip if Class column already contains Missing subclass
+if (static::hasColumnEnumValue($tableName, 'Class', MissingDemonstrationSkill::class)) {
+    printf("Skipping migration because column `%s`.`Class` already has value '%s'\n", $tableName, MissingDemonstrationSkill::class);
+    return static::STATUS_SKIPPED;
+}
+
+// add new Class value
+static::addColumnEnumValue($tableName, 'Class', MissingDemonstrationSkill::class);
+static::addColumnEnumValue($historyTableName, 'Class', MissingDemonstrationSkill::class);
+
+// migrate legacy missing demonstrations
+DB::nonQuery(
+    'UPDATE `%s` SET Class = "%s", DemonstratedLevel = NULL WHERE Class = "%s" AND DemonstratedLevel = 0',
+    [
+        $tableName,
+        DB::escape(MissingDemonstrationSkill::class),
+        DB::escape(DemonstrationSkill::class)
+    ]
+);
+printf(
+    "Updated %u DemonstrationSkill records with Rating = 0 to MissingDemonstrationSkill class\n",
+    DB::affectedRows()
+);