diff --git a/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/Utilities.java b/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/Utilities.java
index 4459a2525..f151d042a 100644
--- a/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/Utilities.java
+++ b/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/Utilities.java
@@ -1912,6 +1912,16 @@ public class Utilities {
         '\u2028', '\u2029', '\u202F', '\u205F', '\u3000');
   }
 
+  public static boolean stringsEqual(String s1, String s2) {
+    if  (s1 == null && s2 == null) {
+      return true;
+    } else if (s1 == null) {
+      return false;
+    } else {
+      return s1.equals(s2);
+    }
+  }
+
 //public static boolean !isWhitespace(String s) {
 //boolean ok = true;
 //for (int i = 0; i < s.length(); i++)
diff --git a/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/i18n/I18nConstants.java b/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/i18n/I18nConstants.java
index f5288f393..699bade3a 100644
--- a/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/i18n/I18nConstants.java
+++ b/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/i18n/I18nConstants.java
@@ -832,6 +832,7 @@ public class I18nConstants {
   public static final String SM_TARGET_TRANSLATE_BINDING_VS_TARGET = "SM_TARGET_TRANSLATE_BINDING_VS_TARGET";
   public static final String SM_TARGET_TRANSLATE_BINDING_VSE_TARGET = "SM_TARGET_TRANSLATE_BINDING_VSE_TARGET";
   public static final String SM_TARGET_TRANSLATE_BINDING_TARGET_WRONG = "SM_TARGET_TRANSLATE_BINDING_TARGET_WRONG";
+  public static final String SM_DEPENDENT_PARAM_TYPE_MISMATCH_DUPLICATE = "SM_DEPENDENT_PARAM_TYPE_MISMATCH_DUPLICATE";
   public static final String CONCEPTMAP_GROUP_SOURCE_MISSING = "CONCEPTMAP_GROUP_SOURCE_MISSING";
   public static final String CONCEPTMAP_GROUP_SOURCE_UNKNOWN = "CONCEPTMAP_GROUP_SOURCE_UNKNOWN";
   public static final String CONCEPTMAP_GROUP_TARGET_MISSING = "CONCEPTMAP_GROUP_TARGET_MISSING";
diff --git a/org.hl7.fhir.utilities/src/main/resources/Messages.properties b/org.hl7.fhir.utilities/src/main/resources/Messages.properties
index a540fe323..901be98f7 100644
--- a/org.hl7.fhir.utilities/src/main/resources/Messages.properties
+++ b/org.hl7.fhir.utilities/src/main/resources/Messages.properties
@@ -895,5 +895,5 @@ CONCEPTMAP_GROUP_TARGET_PROPERTY_TYPE_MISMATCH = The type of this property shoul
 CONCEPTMAP_GROUP_TARGET_PROPERTY_TYPE_NO_SYSTEM = Since no system has been provided, a plain code cannot be used
 CONCEPTMAP_GROUP_TARGET_PROPERTY_CODE_INVALID = The code {0} is invalid in the system {1}
 CONCEPTMAP_GROUP_TARGET_PROPERTY_TYPE_UNKNOWN_SYSTEM = The system {0} is unknown, so code values can''t be checked
-
+SM_DEPENDENT_PARAM_TYPE_MISMATCH_DUPLICATE = The group {0} has already been used with different parameters, so the type checking may be incorrect (other = [{1}]; this = [{2}]) 
  
\ No newline at end of file
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/instance/type/StructureMapValidator.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/instance/type/StructureMapValidator.java
index 1a296f910..b31915f38 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/instance/type/StructureMapValidator.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/instance/type/StructureMapValidator.java
@@ -176,6 +176,22 @@ public class StructureMapValidator extends BaseValidator {
       return null;
     }
 
+    public String summary() {
+      return mode+" "+getWorkingType()+" "+name;
+    }
+
+    public boolean matches(VariableDefn other) {
+      if (!(name.equals(other.name) && mode.equals(other.mode))) {
+        return false;
+      }
+      if (sd == null && other.sd == null) {
+        return true;
+      } else if (sd == null || other.sd == null) {
+        return false;
+      }
+      return sd.getUrl().equals(other.sd.getUrl()) && ed.getPath().equals(other.ed.getPath()) && Utilities.stringsEqual(type, other.type);
+    }
+
   }
 
   public class VariableSet {
@@ -234,6 +250,26 @@ public class StructureMapValidator extends BaseValidator {
       vn.name = pname;
       list.add(vn);
     }
+
+    public String summary() {
+      CommaSeparatedStringBuilder b = new CommaSeparatedStringBuilder();
+      for (VariableDefn v : list) {
+        b.append(v.summary());
+      }
+      return b.toString();
+    }
+
+    public boolean matches(VariableSet other) {
+      if (list.size() != other.list.size()) {
+        return false;
+      }
+      for (int i = 0; i < list.size(); i++) {
+        if (!list.get(i).matches(other.list.get(i))) {
+          return false;
+        }
+      }
+      return true;
+    }
   }
 
   private static final boolean SOURCE = true;
@@ -485,7 +521,7 @@ public class StructureMapValidator extends BaseValidator {
       cc++;
     }
     
-    // process the targets
+    // process the nested rules
     List<Element> rules = rule.getChildrenByName("rule");
     cc = 0;
     for (Element child : rules) {
@@ -901,7 +937,23 @@ public class StructureMapValidator extends BaseValidator {
     } else {
       for (ElementDefinition t : children) {
         if (t.getNameBase().equals(element)) {
-          result.add(new ElementDefinitionSource(sd, t));
+          if (t.hasContentReference()) {
+            String url = t.getContentReference().substring(0, t.getContentReference().indexOf("#"));
+            String path = t.getContentReference().substring(t.getContentReference().indexOf("#")+1);
+            StructureDefinition sdt = "".equals(url) || url.equals(sd.getUrl()) ? sd : context.fetchResource(StructureDefinition.class, url);
+            if (sdt == null) {
+              throw new Error("Unable to resolve "+url);
+            } else {
+              ElementDefinition t2 = sdt.getSnapshot().getElementByPath(path);
+              if (t2 == null) {
+                throw new Error("Unable to resolve "+path+" in "+url);
+              } else {
+                result.add(new ElementDefinitionSource(sdt, t2));
+              }
+            }
+          } else {
+            result.add(new ElementDefinitionSource(sd, t));
+          }
         }
       }
     }
@@ -987,7 +1039,8 @@ public class StructureMapValidator extends BaseValidator {
           if (ok && grp.hasUserData("element.source")) {
             Element g = (Element) grp.getUserData("element.source");
             if (g.hasUserData("structuremap.parameters")) {
-              throw new Error("bang! - this situation is not handled");
+              VariableSet pvars = (VariableSet) g.getUserData("structuremap.parameters");
+              rule(errors, "2023-03-01", IssueType.INVALID, dependent.line(), dependent.col(), stack.getLiteralPath(), pvars.matches(lvars), I18nConstants.SM_DEPENDENT_PARAM_TYPE_MISMATCH_DUPLICATE, grp.getName(), pvars.summary(), lvars.summary());
             } else {
               g.setUserData("structuremap.parameters", lvars);
             }