diff -U0 between postfix@.service and postfix.service, to generate one from another

--- postfix.service
+++ postfix@.service
@@ -2 +2 @@
-Description=Postfix Mail Transport Agent (main/default instance)
+Description=Postfix Mail Transport Agent (instance %i, /etc/postfix-%I)
@@ -11,3 +11,4 @@
-ConditionPathExists=/etc/postfix/main.cf
-# pre-3.9.1-7 multi-instance setup:
-Conflicts=postfix@-.service
+PartOf=postfix.service
+Before=postfix.service
+ReloadPropagatedFrom=postfix.service
+AssertPathExists=/etc/postfix-%I/main.cf
@@ -17,2 +18,2 @@
-# Force operations on single default instance, do not run postmulti wrapper
-Environment=MAIL_CONFIG=/etc/postfix
+# Force operations on single non-default instance
+Environment=MAIL_CONFIG=/etc/postfix-%I