diff --git a/src/blueapi/cli/cli.py b/src/blueapi/cli/cli.py
index db8a22d1c..e2b586232 100644
--- a/src/blueapi/cli/cli.py
+++ b/src/blueapi/cli/cli.py
@@ -11,6 +11,7 @@
 from bluesky_stomp.models import Broker
 from observability_utils.tracing import setup_tracing
 from pydantic import ValidationError
+from pydantic_settings.sources import PathType
 from requests.exceptions import ConnectionError
 
 from blueapi import __version__
@@ -32,7 +33,7 @@
     "-c", "--config", type=Path, help="Path to configuration YAML file", multiple=True
 )
 @click.pass_context
-def main(ctx: click.Context, config: Path | None | tuple[Path, ...]) -> None:
+def main(ctx: click.Context, config: PathType) -> None:
     # Override default yaml_file path in the model_config if `config` is provided
     ApplicationConfig.model_config["yaml_file"] = config
     app_config = ApplicationConfig()  # Instantiates with customized sources
diff --git a/src/blueapi/config.py b/src/blueapi/config.py
index 2dccd12fd..f63bd5fd6 100644
--- a/src/blueapi/config.py
+++ b/src/blueapi/config.py
@@ -95,7 +95,9 @@ class ApplicationConfig(BaseSettings, cli_parse_args=True, cli_prog_name="blueap
     )
 
     @classmethod
-    def customize_sources(cls, init_settings, env_settings, file_secret_settings):
+    def settings_customize_sources(
+        cls, init_settings, env_settings, file_secret_settings
+    ):
         path = cls.model_config.get("yaml_file")
         return (
             init_settings,
diff --git a/src/blueapi/service/interface.py b/src/blueapi/service/interface.py
index f968fd925..9cfbe6116 100644
--- a/src/blueapi/service/interface.py
+++ b/src/blueapi/service/interface.py
@@ -15,7 +15,11 @@
 from blueapi.worker.task_worker import TaskWorker, TrackableTask
 
 """This module provides interface between web application and underlying Bluesky
-context and worker"""
+context and worker
+
+the _CONFIG global variable is used by the subprocess only
+
+"""
 
 
 _CONFIG: ApplicationConfig = ApplicationConfig()
@@ -26,6 +30,10 @@ def config() -> ApplicationConfig:
 
 
 def set_config(new_config: ApplicationConfig):
+    """
+    This is a setter function that the main process uses
+    to pass the config into the subprocess
+    """
     global _CONFIG
 
     _CONFIG = new_config