Occasionally, defining characters’ relationships will give way to how they speak to one another. 

Lisa is the disciplinarian to Sasha and especially to Dina, who is brash and immature. Note that Dina’s excessive profanity helps us to know (without seeing her name above her dialogue) that she is the one talking.

Lisa sounds especially mom-ish when she says “TIME OUT!” — so much so that Dina even replies, “We’re not your damn kids!”

This is a great example of how to ensure the reader knows exactly who’s speaking in a scene with 2 or more characters.