ansible var array override

defaults_main.yml

program:
  name: defaultname
  option1: default
  option2: default
  option3: default

inventory.yml

program:
  name: groupname
  option2: group

playbook.yml

---
- hosts: hostgroup
  vars:
    program:
      name: customname
      option1: customoption

Results.txt

#Expected Results#
program:
  name: customname
  option1: customoption
  option2: group
  option3: default
  
#Actual Results#
program:
  name: customname
  option1: customoption