diff --git a/include/ircd/m/event/append.h b/include/ircd/m/event/append.h
index d3519207b..474017d57 100644
--- a/include/ircd/m/event/append.h
+++ b/include/ircd/m/event/append.h
@@ -41,6 +41,8 @@ struct ircd::m::event::append
 	bool is_invisible(const event &, const opts &) const;
 	bool is_excluded(const event &, const opts &) const;
 
+	bool bundle_replace(json::stack::object &, const event &, const opts &);
+	void _relations(json::stack::object &, const event &, const opts &);
 	void _age(json::stack::object &, const event &, const opts &);
 	void _txnid(json::stack::object &, const event &, const opts &);
 	void _prev_state(json::stack::object &, const event &, const opts &);
@@ -72,6 +74,8 @@ struct ircd::m::event::append::opts
 	bool query_prev_state {true};
 	bool query_redacted {true};
 	bool query_visible {false};
+	bool bundle_all {false};
+	bool bundle_replace {false};
 };
 
 inline
diff --git a/matrix/event_append.cc b/matrix/event_append.cc
index 4157e1b90..d4ec165f6 100644
--- a/matrix/event_append.cc
+++ b/matrix/event_append.cc
@@ -187,7 +187,7 @@ ircd::m::event::append::_unsigned(json::stack::object &out,
 
 	_age(object, event, opts);
 	_txnid(object, event, opts);
-
+	_relations(object, event, opts);
 	if(defined(json::get<"state_key"_>(event)))
 		_prev_state(object, event, opts);
 }
@@ -197,7 +197,7 @@ ircd::m::event::append::_prev_state(json::stack::object &out,
                                     const event &event,
                                     const opts &opts)
 {
-	assert(defined(json::get<"state_key"_>(event)))
+	assert(defined(json::get<"state_key"_>(event)));
 
 	const bool query_prev_state
 	{
@@ -339,6 +339,68 @@ ircd::m::event::append::_age(json::stack::object &out,
 	};
 }
 
+void
+ircd::m::event::append::_relations(json::stack::object &out,
+                                   const event &event,
+                                   const opts &opts)
+{
+	assert(out.s);
+	json::stack::checkpoint cp
+	{
+		*out.s, false
+	};
+
+	json::stack::object object
+	{
+		out, "m.relations"
+	};
+
+	bool commit
+	{
+		cp.committing()
+	};
+
+	if(opts.bundle_all || opts.bundle_replace)
+		commit |= bundle_replace(object, event, opts);
+
+	cp.committing(commit);
+}
+
+bool
+ircd::m::event::append::bundle_replace(json::stack::object &out,
+                                       const event &event,
+                                       const opts &opts)
+{
+	const m::replaced replaced
+	{
+		opts.event_idx, m::replaced::latest
+	};
+
+	const event::idx &replace_idx
+	{
+		replaced
+	};
+
+	if(likely(!replace_idx))
+		return false;
+
+	const m::event::fetch replace
+	{
+		std::nothrow, replace_idx
+	};
+
+	if(unlikely(!replace.valid))
+		return false;
+
+	json::stack::object object
+	{
+		out, "m.replace"
+	};
+
+	object.append(replace);
+	return true;
+}
+
 bool
 ircd::m::event::append::is_excluded(const event &event,
                                     const opts &opts)