requirements for appying for S-TYPE visa

My husband is a filipino working in china,a Z-type visa holder. My kids are a homeschollers here in mnl.we wanted to stay with their father in Shenzhen.but we are also required by the school to take their exams here once a year,a friend told us that we can apply for an S-TYPE, we have been in PRC several times as a tourist,we are only given a double entry for 2 mos.is it possible that we can be granted a much longer one and if possible a multiple?