diff --git a/sdv/multi_table/hma.py b/sdv/multi_table/hma.py
index b251bf312..f7c4ca26a 100644
--- a/sdv/multi_table/hma.py
+++ b/sdv/multi_table/hma.py
@@ -160,7 +160,7 @@ def __init__(self, metadata, locales=['en_US'], verbose=True):
         self._augmented_tables = []
         self._learned_relationships = 0
         self._default_parameters = {}
-        self.parent_extended_columns = defaultdict(list)
+        self._parent_extended_columns = defaultdict(list)
         self.verbose = verbose
         BaseHierarchicalSampler.__init__(
             self, self.metadata, self._table_synthesizers, self._table_sizes
@@ -217,8 +217,8 @@ def _get_distributions(self):
         distributions = {}
         for table in self.metadata.tables:
             parameters = self.get_table_parameters(table)
-            synthesizer_parameter = parameters.get('synthesizer_parameters', {})
-            distributions[table] = synthesizer_parameter.get('default_distribution', None)
+            synthesizer_parameters = parameters.get('synthesizer_parameters', {})
+            distributions[table] = synthesizer_parameters.get('default_distribution', None)
 
         return distributions
 
@@ -273,10 +273,10 @@ def preprocess(self, data):
     def _set_extended_columns_distributions(self, synthesizer, table_name, valid_columns):
         numerical_distributions = {}
         if (
-            table_name in self.parent_extended_columns
-            and len(self.parent_extended_columns[table_name]) > 0
+            table_name in self._parent_extended_columns
+            and len(self._parent_extended_columns[table_name]) > 0
         ):
-            for extended_column in self.parent_extended_columns[table_name]:
+            for extended_column in self._parent_extended_columns[table_name]:
                 if extended_column in valid_columns:
                     numerical_distributions[extended_column] = 'truncnorm'
 
@@ -411,7 +411,7 @@ def _augment_table(self, table, tables, table_name):
                 self._min_child_rows[num_rows_key] = table[num_rows_key].min()
 
                 if len(extension.columns) > 0:
-                    self.parent_extended_columns[table_name].extend(list(extension.columns))
+                    self._parent_extended_columns[table_name].extend(list(extension.columns))
 
                 tables[table_name] = table
                 self._learned_relationships += 1