I JUST HAD THE WORST BEST IDEA FOR AN EVENT
Mmkay y'all listen up
So by chance, Ran and Yukina's dads meet. They talk and stuff, and probably become friends or something.
During that time, Lisa and Moca happen to be in the area and hear the conversation between the dads. They hatch up a masterplan to use the dad's friendship as a way to get their band's vocalists to get along for once.
Chaos ensues.