diff --git a/src/integrationtest/data_classes.py b/src/integrationtest/data_classes.py
index 5419f8d..6a4f7fe 100755
--- a/src/integrationtest/data_classes.py
+++ b/src/integrationtest/data_classes.py
@@ -9,15 +9,18 @@ class DROMap_config:
     app_host: str = "localhost"
     eth_protocol: str = "udp"
     flx_mode: str = "fix_rate"
+    crate_id_offset: int = 1
+    slot_id: int = 0
 
 
 # 27-Aug-2025, KAB: added derived classes to handle various types of configuration
 # substitutions.  The attribute_substitution class handles cases in which we
 # just need to replace simple value(s) for attribute(s) in a config object.
 # The relationship_substitution class handles cases in which the new referenced "value"
-# is a configuration object. And, the list_element_substitution class handles cases in
+# is a configuration object. The list_element_substitution class handles cases in
 # which the data item that we want to modify is an entry in a list within the specified
-# configuration object.
+# configuration object. And, the list_element_addition class handles cases in which
+# we want to add a data item to a list within the specified configuration object.
 @dataclass
 class config_substitution:
     obj_class: str
@@ -37,6 +40,11 @@ class relationship_substitution(config_substitution):
 class list_element_substitution(relationship_substitution):
     list_index: int = 0
 
+@dataclass
+class list_element_addition(config_substitution):
+    rel_name: str = ""
+    additional_object_class: str = ""
+    additional_object_id: str = ""
 
 @dataclass
 class drunc_config:
diff --git a/src/integrationtest/integrationtest_drunc.py b/src/integrationtest/integrationtest_drunc.py
index 854ea60..f72647a 100755
--- a/src/integrationtest/integrationtest_drunc.py
+++ b/src/integrationtest/integrationtest_drunc.py
@@ -12,6 +12,7 @@
     attribute_substitution,
     relationship_substitution,
     list_element_substitution,
+    list_element_addition,
 )
 from daqconf.generate_hwmap import generate_hwmap
 from daqconf.generate import (
@@ -123,6 +124,8 @@ def create_config_files(request, tmp_path_factory):
                         dro_map_config.app_host,
                         dro_map_config.eth_protocol,
                         dro_map_config.flx_mode,
+                        dro_map_config.crate_id_offset,
+                        dro_map_config.slot_id,
                     )
 
             if not file_exists(readout_db):
@@ -199,7 +202,12 @@ def create_config_files(request, tmp_path_factory):
 
     def apply_update(obj, substitution):
         # 27-Aug-2025, KAB: modified this code to support different types of substitutions
-        if isinstance(substitution, list_element_substitution):
+        if isinstance(substitution, list_element_addition):
+            additional_obj = db.get_dal(substitution.additional_object_class, substitution.additional_object_id)
+            the_list = getattr(obj, substitution.rel_name)
+            the_list.append(additional_obj)
+            setattr(obj, substitution.rel_name, the_list)
+        elif isinstance(substitution, list_element_substitution):
             replacement_obj = db.get_dal(substitution.replacement_object_class, substitution.replacement_object_id)
             the_list = getattr(obj, substitution.rel_name)
             the_list[substitution.list_index] = replacement_obj