When a teacher from HSFG visits DDs primary school the girls are asked a number of questions including who they would like to be with. It's not unheard of for HSFG to put all 4 girls together though they may split them into 2 tutor groups. If you or your DD have a preference contact the office or Head of Year, I'm sure they will be more than accommodating.
DDs usually find out which Tutor group they will be in on the Taster day.
DDS are also in a Tech group for art, design, food tech, ICT & PE which is a different mix of girls across several tutor groups, so again if you or your DD have a request contact them!