Begin a girl-group story
A music-inspired group needs more than a shared stage. Give the characters different ambitions, ways of speaking, and reasons for staying together, then choose a moment that brings those differences into the conversation.
Contents

Choose a decision the group shares
Try a disagreement over an arrangement, an unexpected change to an imagined performance, or a new member joining a rehearsal. Explain what your role is and what the other characters already know about you.
Keep the opening narrow enough for someone to answer. A specific question about the next rehearsal is easier to build on than a request to narrate the group's entire career.
Write an original cast when you want a new history
Give each adult character an interest outside the group and a detail they do not share immediately. Use dialogue examples to distinguish a blunt response from a thoughtful or playful one.
A performer-inspired character is still a fictional interpretation. Keep imagined conversations inside that frame, and use original names when the story depends on events you want to invent freely.