diff --git a/timely/src/dataflow/scope.rs b/timely/src/dataflow/scope.rs
index fb922a988..eceed1686 100644
--- a/timely/src/dataflow/scope.rs
+++ b/timely/src/dataflow/scope.rs
@@ -116,12 +116,7 @@ impl<'scope, T: Timestamp> Scope<'scope, T> {
         let path = slot.addr();
         let identifier = slot.identifier();
 
-        let type_name = std::any::type_name::<T2>();
-        let summary_logging = self.worker().logger_for(&format!("timely/summary/{type_name}"));
-
-        let subgraph = RefCell::new(SubgraphBuilder::new_from(
-            path, identifier, self.worker().logging(), summary_logging, name,
-        ));
+        let subgraph = RefCell::new(SubgraphBuilder::new_from(path, identifier, name));
 
         let child = Scope { subgraph: &subgraph, worker: self.worker };
 
diff --git a/timely/src/progress/subgraph.rs b/timely/src/progress/subgraph.rs
index 7fb289f97..393223f53 100644
--- a/timely/src/progress/subgraph.rs
+++ b/timely/src/progress/subgraph.rs
@@ -52,8 +52,8 @@ where
     /// A global identifier for this subgraph.
     identifier: usize,
 
-    // handles to the children of the scope. index i corresponds to entry i-1, unless things change.
-    children: Vec<PerOperatorState<TInner>>,
+    // Deferred children: (operator, index, identifier). Built into PerOperatorState at build time.
+    children: Vec<(Box<dyn Operate<TInner>>, usize, usize)>,
     child_count: usize,
 
     edge_stash: Vec<(Source, Target)>,
@@ -64,10 +64,6 @@ where
     // expressed capabilities, used to filter changes against.
     outputs: usize,
 
-    /// Logging handle
-    logging: Option<Logger>,
-    /// Typed logging handle for operator summaries.
-    summary_logging: Option<SummaryLogger<TInner::Summary>>,
 }
 
 impl<TInner> SubgraphBuilder<TInner>
@@ -99,14 +95,10 @@ where
     pub fn new_from(
         path: Rc<[usize]>,
         identifier: usize,
-        logging: Option<Logger>,
-        summary_logging: Option<SummaryLogger<TInner::Summary>>,
         name: &str,
     )
         -> SubgraphBuilder<TInner>
     {
-        // Put an empty placeholder for "outer scope" representative.
-        let children = vec![PerOperatorState::empty(0, 0)];
         let index = path[path.len() - 1];
 
         SubgraphBuilder {
@@ -114,13 +106,11 @@ where
             path,
             index,
             identifier,
-            children,
+            children: Vec::new(),
             child_count: 1,
             edge_stash: Vec::new(),
             input_messages: Vec::new(),
             outputs: 0,
-            logging,
-            summary_logging,
         }
     }
 
@@ -131,20 +121,10 @@ where
     }
 
     /// Adds a new child to the subgraph.
+    ///
+    /// The child will be initialized and logged when [`build`] is called.
     pub fn add_child(&mut self, child: Box<dyn Operate<TInner>>, index: usize, identifier: usize) {
-        let child = PerOperatorState::new(child, index, identifier, self.logging.clone(), &mut self.summary_logging);
-        if let Some(l) = &mut self.logging {
-            let mut child_path = Vec::with_capacity(self.path.len() + 1);
-            child_path.extend_from_slice(&self.path[..]);
-            child_path.push(index);
-
-            l.log(crate::logging::OperatesEvent {
-                id: identifier,
-                addr: child_path,
-                name: child.name.to_owned(),
-            });
-        }
-        self.children.push(child);
+        self.children.push((child, index, identifier));
     }
 
     /// Now that initialization is complete, actually build a subgraph.
@@ -154,41 +134,57 @@ where
         // we also need to determine what to return as a summary and initial capabilities, which
         // will depend on child summaries and capabilities, as well as edges in the subgraph.
 
-        // perhaps first check that the children are sanely identified
-        self.children.sort_unstable_by(|x,y| x.index.cmp(&y.index));
-        assert!(self.children.iter().enumerate().all(|(i,x)| i == x.index));
-
         let inputs = self.input_messages.len();
         let outputs = self.outputs;
 
-        // Create empty child zero representative.
-        self.children[0] = PerOperatorState::empty(outputs, inputs);
+        let type_name = std::any::type_name::<TInner>();
+        let mut logging = worker.logging();
+        let mut summary_logging = worker.logger_for(&format!("timely/summary/{type_name}"));
+
+        // Sort stashed children by index, and preface with a child zero mirroring the subgraph shape.
+        self.children.sort_unstable_by_key(|&(_, index, _)| index);
+        let mut children: Vec<_> = [PerOperatorState::empty(outputs, inputs)]
+            .into_iter()
+            .chain(self.children.into_iter().map(|(operator, index, identifier)| {
+                let child = PerOperatorState::new(operator, index, identifier, logging.clone(), &mut summary_logging);
+                if let Some(l) = &mut logging {
+                    let mut child_path = Vec::with_capacity(self.path.len() + 1);
+                    child_path.extend_from_slice(&self.path[..]);
+                    child_path.push(index);
+                    l.log(crate::logging::OperatesEvent {
+                        id: identifier,
+                        addr: child_path,
+                        name: child.name.to_owned(),
+                    });
+                }
+                child
+            }))
+            .collect();
+        assert!(children.iter().enumerate().all(|(i,x)| i == x.index));
 
         let mut builder = reachability::Builder::new();
 
         // Child 0 has `inputs` outputs and `outputs` inputs, not yet connected.
         let summary = (0..outputs).map(|_| PortConnectivity::default()).collect();
         builder.add_node(0, outputs, inputs, summary);
-        for (index, child) in self.children.iter().enumerate().skip(1) {
+        for (index, child) in children.iter().enumerate().skip(1) {
             builder.add_node(index, child.inputs, child.outputs, child.internal_summary.clone());
         }
 
         for (source, target) in self.edge_stash {
-            self.children[source.node].edges[source.port].push(target);
+            children[source.node].edges[source.port].push(target);
             builder.add_edge(source, target);
         }
 
-        // The `None` argument is optional logging infrastructure.
-        let type_name = std::any::type_name::<TInner>();
         let reachability_logging =
         worker.logger_for(&format!("timely/reachability/{type_name}"))
               .map(|logger| reachability::logging::TrackerLogger::new(self.identifier, logger));
         let progress_logging = worker.logger_for(&format!("timely/progress/{type_name}"));
         let (tracker, scope_summary) = builder.build(reachability_logging);
 
-        let progcaster = Progcaster::new(worker, Rc::clone(&self.path), self.identifier, self.logging.clone(), progress_logging);
+        let progcaster = Progcaster::new(worker, Rc::clone(&self.path), self.identifier, logging, progress_logging);
 
-        let mut incomplete = vec![true; self.children.len()];
+        let mut incomplete = vec![true; children.len()];
         incomplete[0] = false;
         let incomplete_count = incomplete.len() - 1;
 
@@ -197,7 +193,7 @@ where
         activations.borrow_mut().activate(&self.path[..]);
 
         // The subgraph's per-input interest is conservatively the max across all children's inputs.
-        let max_interest = self.children.iter()
+        let max_interest = children.iter()
             .flat_map(|c| c.notify.iter().copied())
             .max()
             .unwrap_or(FrontierInterest::Never);
@@ -213,7 +209,7 @@ where
             activations,
             temp_active: BinaryHeap::new(),
             maybe_shutdown: Vec::new(),
-            children: self.children,
+            children,
             input_messages: self.input_messages,
             output_capabilities: vec![MutableAntichain::new(); self.outputs],
 
diff --git a/timely/src/worker.rs b/timely/src/worker.rs
index c2170d281..2ec4fbeb6 100644
--- a/timely/src/worker.rs
+++ b/timely/src/worker.rs
@@ -621,9 +621,7 @@ impl Worker {
         let addr = vec![dataflow_index].into();
         let identifier = self.new_identifier();
 
-        let type_name = std::any::type_name::<T>();
-        let summary_logging  = self.logger_for(&format!("timely/summary/{}", type_name));
-        let subscope = SubgraphBuilder::new_from(addr, identifier, logging.clone(), summary_logging, name);
+        let subscope = SubgraphBuilder::new_from(addr, identifier, name);
         let subscope = RefCell::new(subscope);
 
         let result = {