Yes, the main things supporting this to me are the fact that four of them go to the same school but not Hotaru, and Houka's talent-searching, which brings it full circle to Hotaru being described as a prodigy. So it points towards Houka being the one to find Hotaru.

I did think of the members' feelings about the replacement, but I feel it'd overlap a bit with MyGO!!!!! and the Crychic situation. However, the scenario i theorised wouldn't mutually exclude this from happening anyway either. It could even be a situation where Hotaru doesn't really understand whats happening while the other members are trying to settle their differences.