Your regularly sounds like something that happens on the weekends. My regular is taking 2 kids to school everyday and leaving my bike parked out in the rain year round. Not all bikes have enough trail room to fit a double legged kickstand and I have never seen a stem lock fitted on anything other than a moederfiets/transportfiets (not a lock smith 'key and lock' but a 'twist' lock to lock the stem to take your kid out of the front seat without the front wheel spinning around on you).

My point is just that if you're planning on replacing a car with a bycicle there are already solved problems for kids transportation.