SBC can cater for PF1-7 exclusive for BNC/BYPL bound trains, PF8-10 cater for YPR bound trains. A train from BYPL cannot enter PF8-10, similarly an incoming train from YPR cannot come on PF1-7, hence there is no common PF for YPR/BYPL trains.
And only PF5-10 can cater for MYS bound trains. This is one of the bottleneck for SBC.