I would ask DD to write a timetable of the average week and how she sees it going at her dad’s and then additional “big days”.
For example:
Mon - dad drives me to school, picks me up after and takes me to tennis
Tue - dad drives me to school, picks me up after, takes me home, dinner together
We’d - dad drives me to school, I do sports, dad comes and watches if it’s a competitive match, we go home together
Thur - dad drives me to school, picks me up after and takes me to hockey practice
fri - dad drives me to school, picks me up and drives me back to Mums house so I can stay the weekend with mum and see my friends.
Halloween; I stay at mums and go out trick or treating with my friends
Sophie’s birthday on Thursday Xth Nov, Dad drives me home so I can attend her birthday gathering and picks me up at 11pm to bring me home.
Then go through each line and explain that:
Dad will never be driving you to school, or picking you up as he has work
Dad will never take you to tennis club, or watch your Wed matches or take you to hockey as he works
Dad will not want to drive you back to mums on Friday nights, or let you stay here for Halloween, or drive you back for Sophie’s birthday, so you will miss all those events.
Maybe she’s ok with walking to school, maybe she’s ok with missing her afterschool activities, maybe she’s really not ok about missing Halloween, or Sophie’s party or having no one support her when she competes at whatever sport.
Let her make her own decision about which parent she lives with, but ensure she has all the facts about what her life will look like, day-to-day.