I can define a variable/list in my main playbook (main.yml) or in my group variables (group_vars/all.yml) but the main.yml variables have precedence over the group variables.

group_vars/all.yml

my_list:
 - "item 1"
 - "item 2"

main.yml

  vars:
    my_list:
      - "item 3"
      - "item 4"

I would like to combine the two but am not sure how to do it. Desired:

my_list: ['item 1', 'item 2', 'item 3', 'item 4']

I have tried adding to the list. For example if main.yml could see group_vars before overwriting (but this example throws an error).

    my_list:
     - "{{ my_list }}"
     - "item 3"
     - "item 4"

I am doing this because I am using code from another repository. I don’t want to make changes to their code, but I do want to update (not overwrite) their variable list.