They sang the backing vocals for her new track Through The Rain and she gave them her expert tips.
She wanted more of that "attitude because we quite like it," from Lemar.
And she loved Marli's singing: "I don't know what you're doing but I love it!" she exclaimed.
And she tried to inspire the girls by saying "put a little hot sauce on it".
Far from being the diva, Mariah seemed really impressed with their performances and left telling them they were all amazing.
And they loved her: "She was brilliant!" said Lemar.