"Girls, what if we do a coordinated spin?", them 2 minutes before getting up on the stage.
I´m not knowledgeable with choreographies and stuff.
But that´s why I would just tell them to play it safe.
Just stand in a half circle behind microphone stands and sing. Maybe do some hand gestures here and there.
When the final chorus explodes, all remove microphones from stands and walk to the front of the stage. Do a horizontal line formation in the front of the stage, sing the last chorus with some hand movements and finish the song.
Yeah. Basic as hell and clique. I know, I know.
But still, that looks way less awkward in my mind.