diff --git a/docs/howitworks.rst b/docs/howitworks.rst
index 5c8bb018..dfe2b2d7 100644
--- a/docs/howitworks.rst
+++ b/docs/howitworks.rst
@@ -445,6 +445,23 @@ also listen on the following handles:
     In this way, the master need never re-send a module it has already sent to
     a direct descendant.
 
+.. currentmodule:: mitogen.core
+.. data:: FORWARD_MODULE
+
+    Receives `(context, fullname)` tuples from its parent and arranges for a
+    :data:`LOAD_MODULE` to be sent towards `context` for the module `fullname`
+    and any related modules. The module must already have been delivered to the
+    current context by its parent in a prior :data:`LOAD_MODULE` message.
+
+    If the receiver is the immediate parent of `context`, then only
+    :data:`LOAD_MODULE` is sent to the child. Otherwise :data:`LOAD_MODULE` is
+    sent to the next closest parent if the module has not previously been sent
+    on that stream, followed by a copy of the :data:`FORWARD_MODULE` message.
+
+    This message is used to recursively preload indirect children with modules,
+    ensuring they are cached and deduplicated at each hop in the chain leading
+    to the target context.
+
 .. currentmodule:: mitogen.core
 .. data:: DETACHING
 
diff --git a/mitogen/core.py b/mitogen/core.py
index 26151cbf..e947ecfe 100644
--- a/mitogen/core.py
+++ b/mitogen/core.py
@@ -75,7 +75,8 @@ DEL_ROUTE = 104
 ALLOCATE_ID = 105
 SHUTDOWN = 106
 LOAD_MODULE = 107
-DETACHING = 108
+FORWARD_MODULE = 108
+DETACHING = 109
 IS_DEAD = 999
 
 try:
diff --git a/mitogen/parent.py b/mitogen/parent.py
index 5cdc89c9..e6d76c6b 100644
--- a/mitogen/parent.py
+++ b/mitogen/parent.py
@@ -1106,6 +1106,12 @@ class ModuleForwarder(object):
         self.router = router
         self.parent_context = parent_context
         self.importer = importer
+        router.add_handler(
+            fn=self._on_forward_module,
+            handle=mitogen.core.FORWARD_MODULE,
+            persist=True,
+            policy=mitogen.core.has_parent_authority,
+        )
         router.add_handler(
             fn=self._on_get_module,
             handle=mitogen.core.GET_MODULE,
@@ -1116,34 +1122,64 @@ class ModuleForwarder(object):
     def __repr__(self):
         return 'ModuleForwarder(%r)' % (self.router,)
 
+    def _on_forward_module(self, msg):
+        if msg.is_dead:
+            return
+
+        context_id_s, fullname = msg.data.partition('\x00')
+        context_id = int(context_id_s)
+        stream = self.router.stream_by_id(context_id)
+        if stream.remote_id == mitogen.parent_id:
+            LOG.error('%r: dropping FORWARD_MODULE(%d, %r): no route to child',
+                      self, context_id, fullname)
+            return
+
+        LOG.debug('%r._on_forward_module() sending %r to %r via %r',
+                  self, fullname, context_id, stream.remote_id)
+        self._send_module_and_related(stream, fullname)
+        if stream.remote_id != context_id:
+            stream._send(
+                mitogen.core.Message(
+                    dst_id=stream.remote_id,
+                    handle=mitogen.core.FORWARD_MODULE,
+                    data=msg.data,
+                )
+            )
+
     def _on_get_module(self, msg):
         LOG.debug('%r._on_get_module(%r)', self, msg)
         if msg.is_dead:
             return
 
         fullname = msg.data
-        callback = lambda: self._on_cache_callback(msg, fullname)
-        self.importer._request_module(fullname, callback)
-
-    def _send_one_module(self, msg, tup):
-        self.router._async_route(
-            mitogen.core.Message.pickled(
-                tup,
-                dst_id=msg.src_id,
-                handle=mitogen.core.LOAD_MODULE,
-            )
+        self.importer._request_module(fullname,
+            lambda: self._on_cache_callback(msg, fullname)
         )
 
     def _on_cache_callback(self, msg, fullname):
         LOG.debug('%r._on_get_module(): sending %r', self, fullname)
+        stream = self.router.stream_by_id(msg.src_id)
+        self._send_module_and_related(stream, fullname)
+
+    def _send_module_and_related(self, stream, fullname):
         tup = self.importer._cache[fullname]
-        if tup is not None:
-            for related in tup[4]:
-                rtup = self.importer._cache.get(related)
-                if not rtup:
-                    LOG.debug('%r._on_get_module(): skipping absent %r',
-                               self, related)
-                    continue
-                self._send_one_module(msg, rtup)
-
-        self._send_one_module(msg, tup)
+        for related in tup[4]:
+            rtup = self.importer._cache.get(related)
+            if rtup:
+                self._send_one_module(stream, rtup)
+            else:
+                LOG.debug('%r._send_module_and_related(%r): absent: %r',
+                           self, fullname, related)
+
+        self._send_one_module(stream, tup)
+
+    def _send_one_module(self, stream, tup):
+        if tup[0] not in stream.sent_modules:
+            stream.sent_modules.add(tup[0])
+            self.router._async_route(
+                mitogen.core.Message.pickled(
+                    tup,
+                    dst_id=stream.remote_id,
+                    handle=mitogen.core.LOAD_MODULE,
+                )
+            )