There are several ways how you can achieve this

- You could use a very wide resolution and use an img2img with the same faces or characters next to each other in a row and set it to about the strength to about .10 to .35 on a scale of 0-1.
- Use famous names in your negative prompt.
- Train your own model or textual inversion model.

Let me know if you need any more tips.
spam fails_task lang_mismatch pii not_appropriate hate_speech sexual_content quality toxicity humor helpfulness creativity violence