If brother or sister is studying in SFA, they will have higher chance.
For SFA and GHS, both of them are of high standard but SFA is much difficult than GHS (I compare the exam papers for both and also the workload)
Even SFA has no secondary school but if studying in this school and the result is not very bad, it is not difficult to get a good secondary school. (because most secondary like to get their students as the std is very high among most primary school)
But you have to prepare no more leisure time for the kids if enroll in both schools. I choose SFA last year as I think it is better for girl to study in co-edu school so they can learn how to communicate with boys.