either you choose hunza or skardu.. you and your family will need more than 7 days to explore both areas together
yes it is safe to take your kids to these places
cars can go till deosai from skardu.. make sure you hire an experienced driver who knows these places... i hope a PW member here has a contact in islamabad
if u choose skardu:
stay in naran first.. its approx 8 hrs away from isl
your next leg will be longer and tougher (naran to skardu) .. it will take you between 8-12 hrs to reach skardu.. depends on road condition, landslide situation etc.. so leave as early as possible ..but do stop at chilas for lunch ..
there plenty of good hotels in skardu.. finding them wont be hard
you can stay 3-4 days there and explore deosai, khaplu, shigar, sheoshar, satpara
for hunza:
stay in naran
from naran: hunza is approx 8 hrs away
while staying in hunza explore altit baltit forts, eagles nest, try going to khunjerab pass as well and naltar valley if you have an extra day
there are a lot of options to stay in hunza.. finding them wont be hard
all the best!