Example of nested playbooks and different ip?

hostname1.yml

- name: this is a play at the top level of a file
  hosts: pre-ip
  remote_user: root
  tasks:
  - name: say hi
    tags: foo
    shell: echo "hi..."

hostname2.yml

- name: this is a play at the top level of a file
  hosts: post-ip
  remote_user: root
  tasks:
  - name: say hi
    tags: foo
    shell: echo "hi..."

hosts

[pre-ip]
hostname1 ansible_host=192.0.2.50
[post-ip]
hostname2 ansible_host=192.0.2.51

playbook.yml

- name: this is a play at the top level of a file
  hosts: pre-ip
  remote_user: root
  tasks:
  - name: say hi
    tags: foo
    shell: echo "hi..."

# and this is how we include another playbook, be careful and
# don't recurse infinitely or anything.  Note you can't use
# any variables in the include path here.
- include: hostname1.yml
- include: hostname2.yml