My guess: Nino, Yotsuba, Ichika, Miku and Itsuki
Nino and Ichika a rough guess, Yotsuba because of the hand gesture, Miku is obvious once you look from side, Itsuki because she's the one speaking.
Honestly, it still baffle me why they even bother doing this at this exact moment in the first place. If it was done earlier like maybe school festival or maybe, during the time their gramps was sick, would have been a lot better but eh, even BK and Lolikano/Rena issues got thrown out of the windows so it just works, I guess.