i'm on my own with 5 dc,2 eldest are teens too.
for discipline,i find the usual grounding and stopping of pocket money works here!
they all have chores to do. daily usual stuff,picking up after themselves etc. if they do this properly,and some extra chores on a saturday,then they get their pocket money
they push the boundaries too far,then it gets cut a little. do it again,it gets stopped for that week.
my 11 yr old always washes kitcen floor,can sort the bins,fold laundry etc. think he enjoys it
the 16 and 14 yr olds can do pretty much anythng,. clean bathroom,ironing,wash car etc. they get no money unless its done to standard either!
i'm strict,but its paying off....