diff --git a/etc/db/database-version.sql b/etc/db/database-version.sql
index 80a1065..10e4844 100644
--- a/etc/db/database-version.sql
+++ b/etc/db/database-version.sql
@@ -1,3 +1,3 @@
-INSERT INTO public.info VALUES ('version', '{"db_schema": "0.3.4"}')
+INSERT INTO public.info VALUES ('version', '{"db_schema": "0.3.5"}')
 ON CONFLICT (key) DO UPDATE
-	SET value = public.info.value || '{"db_schema": "0.3.4"}' WHERE public.info.key = 'version';
+	SET value = public.info.value || '{"db_schema": "0.3.5"}' WHERE public.info.key = 'version';
diff --git a/etc/db/upgrades/upgrade18-v0.3.5-label_in_sequence-function.sql b/etc/db/upgrades/upgrade18-v0.3.5-label_in_sequence-function.sql
new file mode 100644
index 0000000..9c1c008
--- /dev/null
+++ b/etc/db/upgrades/upgrade18-v0.3.5-label_in_sequence-function.sql
@@ -0,0 +1,158 @@
+-- Fix not being able to edit a time-based event.
+--
+-- New schema version: 0.3.5
+--
+-- ATTENTION:
+--
+-- ENSURE YOU HAVE BACKED UP THE DATABASE BEFORE RUNNING THIS SCRIPT.
+--
+--
+-- NOTE: This upgrade affects all schemas in the database.
+-- NOTE: Each application starts a transaction, which must be committed
+-- or rolled back.
+--
+-- The function label_in_sequence(integer, text) was missing for the
+-- production schemas. This patch (re-)defines the function as well
+-- as other function that depend on it (otherwise it does not get
+-- picked up).
+--
+-- To apply, run as the dougal user:
+--
+-- psql <<EOF
+-- \i $THIS_FILE
+-- COMMIT;
+-- EOF
+--
+-- NOTE: It can be applied multiple times without ill effect.
+--
+
+BEGIN;
+
+CREATE OR REPLACE PROCEDURE show_notice (notice text) AS $$
+BEGIN
+	RAISE NOTICE '%', notice;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE PROCEDURE pg_temp.upgrade_survey_schema (schema_name text) AS $$
+BEGIN
+
+	RAISE NOTICE 'Updating schema %', schema_name;
+	-- We need to set the search path because some of the trigger
+	-- functions reference other tables in survey schemas assuming
+	-- they are in the search path.
+	EXECUTE format('SET search_path TO %I,public', schema_name);
+
+
+	CREATE OR REPLACE FUNCTION label_in_sequence(_sequence integer, _label text) RETURNS event_log
+	LANGUAGE sql
+	AS $inner$
+		SELECT * FROM event_log WHERE sequence = _sequence AND _label = ANY(labels);
+	$inner$;
+
+	-- We need to redefine the functions / procedures that call label_in_sequence
+
+	CREATE OR REPLACE PROCEDURE handle_final_line_events(IN _seq integer, IN _label text, IN _column text)
+	LANGUAGE plpgsql
+	AS $inner$
+
+	DECLARE
+	_line final_lines_summary%ROWTYPE;
+	_column_value integer;
+	_tg_name text := 'final_line';
+	_event event_log%ROWTYPE;
+	event_id integer;
+	BEGIN
+
+		SELECT * INTO _line FROM final_lines_summary WHERE sequence = _seq;
+		_event := label_in_sequence(_seq, _label);
+		_column_value := row_to_json(_line)->>_column;
+
+		--RAISE NOTICE '% is %', _label, _event;
+		--RAISE NOTICE 'Line is %', _line;
+		--RAISE NOTICE '% is % (%)', _column, _column_value, _label;
+
+		IF _event IS NULL THEN
+			--RAISE NOTICE 'We will populate the event log from the sequence data';
+
+			INSERT INTO event_log (sequence, point, remarks, labels, meta)
+			VALUES (
+				-- The sequence
+				_seq,
+				-- The shotpoint
+				_column_value,
+				-- Remark. Something like "FSP <linename>"
+				format('%s %s', _label, (SELECT meta->>'lineName' FROM final_lines WHERE sequence = _seq)),
+				-- Label
+				ARRAY[_label],
+				-- Meta. Something like {"auto" : {"FSP" : "final_line"}}
+				json_build_object('auto', json_build_object(_label, _tg_name))
+			);
+
+		ELSE
+			--RAISE NOTICE 'We may populate the sequence meta from the event log';
+			--RAISE NOTICE 'Unless the event log was populated by us previously';
+			--RAISE NOTICE 'Populated by us previously? %', _event.meta->'auto'->>_label = _tg_name;
+
+			IF _event.meta->'auto'->>_label IS DISTINCT FROM _tg_name THEN
+
+				--RAISE NOTICE 'Adding % found in events log to final_line meta', _label;
+				UPDATE final_lines
+				SET meta = jsonb_set(meta, ARRAY[_label], to_jsonb(_event.point))
+				WHERE sequence = _seq;
+
+			END IF;
+
+		END IF;
+	END;
+	$inner$;
+
+	CREATE OR REPLACE PROCEDURE final_line_post_import(IN _seq integer)
+	LANGUAGE plpgsql
+	AS $inner$
+	BEGIN
+
+	CALL handle_final_line_events(_seq, 'FSP', 'fsp');
+	CALL handle_final_line_events(_seq, 'FGSP', 'fsp');
+	CALL handle_final_line_events(_seq, 'LGSP', 'lsp');
+	CALL handle_final_line_events(_seq, 'LSP', 'lsp');
+
+	END;
+	$inner$;
+
+
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE PROCEDURE pg_temp.upgrade_18 () AS $$
+DECLARE
+	row RECORD;
+BEGIN
+	FOR row IN
+		SELECT schema_name FROM information_schema.schemata
+		WHERE schema_name LIKE 'survey_%'
+		ORDER BY schema_name
+	LOOP
+		CALL pg_temp.upgrade_survey_schema(row.schema_name);
+	END LOOP;
+END;
+$$ LANGUAGE plpgsql;
+
+CALL pg_temp.upgrade_18();
+
+CALL show_notice('Cleaning up');
+DROP PROCEDURE pg_temp.upgrade_survey_schema (schema_name text);
+DROP PROCEDURE pg_temp.upgrade_18 ();
+
+CALL show_notice('Updating db_schema version');
+INSERT INTO public.info VALUES ('version', '{"db_schema": "0.3.5"}')
+ON CONFLICT (key) DO UPDATE
+	SET value = public.info.value || '{"db_schema": "0.3.5"}' WHERE public.info.key = 'version';
+
+
+CALL show_notice('All done. You may now run "COMMIT;" to persist the changes');
+DROP PROCEDURE show_notice (notice text);
+
+--
+--NOTE Run `COMMIT;` now if all went well
+--