diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index f5dfbec..0540b84 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -1003,15 +1003,35 @@
   Returns:
     The merged dynamic partition info dictionary.
   """
-  merged_dict = {}
+
+  def uniq_concat(a, b):
+    combined = set(a.split(" "))
+    combined.update(set(b.split(" ")))
+    combined = [item.strip() for item in combined if item.strip()]
+    return " ".join(sorted(combined))
+
+  if (framework_dict.get("use_dynamic_partitions") !=
+      "true") or (vendor_dict.get("use_dynamic_partitions") != "true"):
+    raise ValueError("Both dictionaries must have use_dynamic_partitions=true")
+
+  merged_dict = {"use_dynamic_partitions": "true"}
+
+  merged_dict["dynamic_partition_list"] = uniq_concat(
+      framework_dict.get("dynamic_partition_list", ""),
+      vendor_dict.get("dynamic_partition_list", ""))
+
+  # Super block devices are defined by the vendor dict.
+  if "super_block_devices" in vendor_dict:
+    merged_dict["super_block_devices"] = vendor_dict["super_block_devices"]
+    for block_device in merged_dict["super_block_devices"].split(" "):
+      key = "super_%s_device_size" % block_device
+      if key not in vendor_dict:
+        raise ValueError("Vendor dict does not contain required key %s." % key)
+      merged_dict[key] = vendor_dict[key]
+
   # Partition groups and group sizes are defined by the vendor dict because
   # these values may vary for each board that uses a shared system image.
   merged_dict["super_partition_groups"] = vendor_dict["super_partition_groups"]
-  framework_dynamic_partition_list = framework_dict.get(
-      "dynamic_partition_list", "")
-  vendor_dynamic_partition_list = vendor_dict.get("dynamic_partition_list", "")
-  merged_dict["dynamic_partition_list"] = ("%s %s" % (
-      framework_dynamic_partition_list, vendor_dynamic_partition_list)).strip()
   for partition_group in merged_dict["super_partition_groups"].split(" "):
     # Set the partition group's size using the value from the vendor dict.
     key = "super_%s_group_size" % partition_group
@@ -1022,15 +1042,16 @@
     # Set the partition group's partition list using a concatenation of the
     # framework and vendor partition lists.
     key = "super_%s_partition_list" % partition_group
-    merged_dict[key] = (
-        "%s %s" %
-        (framework_dict.get(key, ""), vendor_dict.get(key, ""))).strip()
+    merged_dict[key] = uniq_concat(
+        framework_dict.get(key, ""), vendor_dict.get(key, ""))
 
-  # Pick virtual ab related flags from vendor dict, if defined.
-  if "virtual_ab" in vendor_dict.keys():
-    merged_dict["virtual_ab"] = vendor_dict["virtual_ab"]
-  if "virtual_ab_retrofit" in vendor_dict.keys():
-    merged_dict["virtual_ab_retrofit"] = vendor_dict["virtual_ab_retrofit"]
+  # Various other flags should be copied from the vendor dict, if defined.
+  for key in ("virtual_ab", "virtual_ab_retrofit", "lpmake",
+              "super_metadata_device", "super_partition_error_limit",
+              "super_partition_size"):
+    if key in vendor_dict.keys():
+      merged_dict[key] = vendor_dict[key]
+
   return merged_dict