Ok, lets try this.

playbooks/groups/backup-server.yml

@@ -8,14 +8,11 @@
   user: root
   gather_facts: True
 
-  vars:
-     base_pkgs_erase: ['firstboot-tui','bluez-utils', 'sendmail']
-# This is here to override the logwatch removal in Redhat vars. 
-
   vars_files: 
    - /srv/web/infra/ansible/vars/global.yml
    - ${private}/vars.yml
    - ${vars}/${ansible_distribution}.yml
+   - ${vars}/backup_server.yml
 
   tasks:
   tasks:

vars/backup_server.yml

@@ -0,0 +1,3 @@
+---
+base_pkgs_erase: ['firstboot-tui','bluez-utils', 'sendmail']
+# This is here to override the logwatch removal in Redhat vars.