Looking at the first grouping, the my diagram was
F–> L–> S (cp: /S–>/L /S–>/F /L–>/F)
T–> S & R (cp: /S or /R –> /T)
/F–> J (cp:/J–>F) (if this was diagramed as F–>/J or J–>/F then both F and J could be out, and it says one of them must attend)
So the last statement “If Sarah does not attend, Jessica will” should be provable .
/S–>/F AND /F–>J