Include tasks from another role in ansible playbook

I'm designing a kind of playbook lib with individual tasks

so in the usual roles repo, I have something like:

roles
├── common
│   └── tasks
│       ├── A.yml
│       ├── B.yml
│       ├── C.yml
│       ├── D.yml
│       ├── login.yml
│       ├── logout.yml
│       └── save.yml
├── custom_stuff_workflow
│   └── tasks
│       └── main.yml
└── other_stuff_workflow
    └── tasks
        └── main.yml

my main.yml in custom_stuff_workflow then contain something like:

---

- include: login.yml
- include: A.yml
- include: C.yml
- include: save.yml
- include: logout.yml

and this one in the other workflow:

---

- include: login.yml
- include: B.yml
- include: A.yml
- include: D.yml
- include: save.yml
- include: logout.yml

I can't find a way to do it in a natural way:
one way that worked was having all tasks in a single role and tagging the relevant tasks while including a custom_stuff_workflow

The problem I have with that is that tags cannot be set in the calling playbook: it's only to be set at command line
as I'm distributing this ansible repo with many people in the company, I can't rely on command line invocations (it would be nice to have a #! header in yml to be processed by ansible-playbook command)

I could also copy the relevant tasks (inside common in the above tree) in each workflow, but I don't want to repeat them around

Can someone see a solution to achieve what I'd like without repeating the tasks over different roles?

I guess the corner stone of my problem is that I define tasks as individual and it looks not natural in ansible…

Thanks a lot

PS: note that the tasks in the workflow have to be done in specific order and the only natural steps to abstract would be the login and save/logout

PPS: I've seen this question How do I call a role from within another role in Ansible? but it does not solve my problem as it's invoking a full role and not a subset of the tasks in a role