diff --git a/src/factory/Convert.cpp b/src/factory/Convert.cpp
index 026ccfe..71ea96e 100644
--- a/src/factory/Convert.cpp
+++ b/src/factory/Convert.cpp
@@ -448,6 +448,8 @@ bool Convert::isCopyUnionCompatible(
     return *(from.get()) == *(to.get());
 }
 
+static PVDataCreatePtr pvDataCreate = getPVDataCreate();
+
 void Convert::copyUnion(PVUnionPtr const & from, PVUnionPtr const & to)
 {
     if(to->isImmutable()) {
@@ -462,14 +464,27 @@ void Convert::copyUnion(PVUnionPtr const & from, PVUnionPtr const & to)
     PVFieldPtr fromValue = from->get();
     if (from->getUnion()->isVariant())
     {
-            to->set(from->get());
+        if (fromValue.get() == 0)
+            to->set(PVField::shared_pointer());
+        else
+        {
+            PVFieldPtr toValue = to->get();
+            if (toValue.get() == 0 || *toValue->getField() != *fromValue->getField())
+            {
+                toValue = pvDataCreate->createPVField(fromValue->getField());
+                to->set(toValue);
+            }
+            copy(fromValue, toValue);
+        }
     }
     else
     {
         if (fromValue.get() == 0)
             to->select(PVUnion::UNDEFINED_INDEX);
         else
-            to->set(from->getSelectedIndex(),from->get());
+        {
+            copy(fromValue, to->select(from->getSelectedIndex()));
+        }
     }
 }
 
diff --git a/src/factory/PVStructureArray.cpp b/src/factory/PVStructureArray.cpp
index 1536ad5..ffb5a37 100644
--- a/src/factory/PVStructureArray.cpp
+++ b/src/factory/PVStructureArray.cpp
@@ -179,7 +179,7 @@ void PVStructureArray::deserialize(ByteBuffer *pbuffer,
             data[i].reset();
         }
         else {
-            if(data[i].get()==NULL) {
+            if(data[i].get()==NULL || !data[i].unique()) {
                 data[i] = pvDataCreate->createPVStructure(structure);
             }
             data[i]->deserialize(pbuffer, pcontrol);
diff --git a/src/factory/PVUnionArray.cpp b/src/factory/PVUnionArray.cpp
index 0239ec1..ed516c6 100644
--- a/src/factory/PVUnionArray.cpp
+++ b/src/factory/PVUnionArray.cpp
@@ -178,7 +178,7 @@ void PVUnionArray::deserialize(ByteBuffer *pbuffer,
             data[i].reset();
         }
         else {
-            if(data[i].get()==NULL) {
+            if(data[i].get()==NULL || !data[i].unique()) {
                 data[i] = pvDataCreate->createPVUnion(punion);
             }
             data[i]->deserialize(pbuffer, pcontrol);