diff --git a/Doc/library/argparse.rst b/Doc/library/argparse.rst
index 102b3e9..2164ec0 100644
--- a/Doc/library/argparse.rst
+++ b/Doc/library/argparse.rst
@@ -351,6 +351,11 @@
 :class:`ArgumentParser` will see two ``-h/--help`` options (one in the parent
 and one in the child) and raise an error.
 
+.. note::
+   You must fully initialize the parsers before passing them via ``parents=``.
+   If you change the parent parsers after the child parser, those changes will
+   not be reflected in the child.
+
 
 formatter_class
 ^^^^^^^^^^^^^^^
diff --git a/Misc/NEWS b/Misc/NEWS
index 4638fd7..babee78 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -162,6 +162,9 @@
 
 - Issue #8982: Improve the documentation for the argparse Namespace object.
 
+- Issue #9343: Document that argparse parent parsers must be configured before
+  their children.
+
 Build
 -----