diff --git a/openvpn/libmapstack.jinja b/openvpn/libmapstack.jinja
index 4e8c7f8..c671c0e 100644
--- a/openvpn/libmapstack.jinja
+++ b/openvpn/libmapstack.jinja
@@ -196,6 +196,19 @@
 {%-           set yaml_names = [yaml_names] %}
 {%-         endif %}
 
+{#-         Try to load a `.yaml.jinja` file for each `.yaml` file #}
+{%-         set all_yaml_names = [] %}
+{%-         for name in yaml_names %}
+{%-           set extension = name.rpartition(".")[2] %}
+{%-           if extension not in ["yaml", "jinja"] %}
+{%-             do all_yaml_names.extend([name ~ ".yaml", name ~ ".yaml.jinja"]) %}
+{%-           elif extension == "yaml" %}
+{%-             do all_yaml_names.extend([name, name ~ ".jinja"]) %}
+{%-           else %}
+{%-             do all_yaml_names.append(name) %}
+{%-           endif %}
+{%-         endfor %}
+
 {#-         `yaml_dirname` can be an empty string with literal path like `myconf.yaml` #}
 {%-         set yaml_dir = [
               param_dir,
@@ -204,15 +217,10 @@
             | select
             | join("/") %}
 
-{%-         for yaml_name in yaml_names %}
-{#-           Make sure to have a `.yaml` extension #}
-{#-           Use `.rpartition` to strip last `.yaml` in `dir.yaml/file.yaml` #}
+{%-         for yaml_name in all_yaml_names %}
 {%-           set yaml_filename = [
                 yaml_dir.rstrip("/"),
-                yaml_name.rpartition(".yaml")
-                | reject("equalto", ".yaml")
-                | join
-                ~ ".yaml"
+                yaml_name
               ]
               | select
               | join("/") %}
diff --git a/openvpn/map.jinja b/openvpn/map.jinja
index 9fdba2b..7340d53 100644
--- a/openvpn/map.jinja
+++ b/openvpn/map.jinja
@@ -38,6 +38,7 @@
 
 {#- Load formula parameters values #}
 {%- set _formula_matchers = ["defaults.yaml"] + map_sources %}
+
 {%- set _formula_settings = mapstack(
       matchers=_formula_matchers,
       dirs=[formula_param_dir],
@@ -59,3 +60,7 @@
 
 {%- do salt["log.debug"]("map.jinja: save parameters in variable 'mapdata'") %}
 {%- set mapdata = _formula_settings["values"] %}
+
+{#- Per formula post-processing of `mapdata` if it exists #}
+{%- do salt["log.debug"]("map.jinja: post-processing of 'mapdata'") %}
+{%- include tplroot ~ "/post-map.jinja" ignore missing %}
diff --git a/openvpn/parameters/defaults.yaml b/openvpn/parameters/defaults.yaml
index c8f563c..f123143 100644
--- a/openvpn/parameters/defaults.yaml
+++ b/openvpn/parameters/defaults.yaml
@@ -1,4 +1,3 @@
-# yamllint disable-file
 # -*- coding: utf-8 -*-
 # vim: ft=yaml
 ---
@@ -14,7 +13,7 @@ values:
   group: nobody
   # None, will default to 'user'
   log_user: ~
-  multi_services: {{ salt['grains.has_value']('systemd') }}
+  multi_services: false
   pkgs: ['openvpn']
   service: openvpn
   service_function: running
diff --git a/openvpn/parameters/defaults.yaml.jinja b/openvpn/parameters/defaults.yaml.jinja
new file mode 100644
index 0000000..3e068d0
--- /dev/null
+++ b/openvpn/parameters/defaults.yaml.jinja
@@ -0,0 +1,15 @@
+{#- -*- coding: utf-8 -*- #}
+{#- vim: ft=jinja #}
+{#-
+    Setup variables after loading `defaults.yaml`.
+
+    This jinja2 file must return a valid `map.jinja` YAML which will
+    be merged into `defaults.yaml`.
+
+    If you do not need to provide calculated defaults, you can remove
+    this file or provide at least an empty dict, e.g.  values: {}
+#}
+---
+values:
+  multi_services: {{ salt['grains.has_value']('systemd') }}
+...