It's happening now and it's been going on for years. Mom used to play piano so the family decides to get a used piano. The next thing you know, Mom is playing again, the older kid is taking lessons from the piano teacher and the toddler is getting lessons from their mother. It's a family project and it's been going on since the early 1700's.
Most piano teachers do not take on students until they are five years old so in the mean time, go for it Mom! Get a used piano, start playing again, help the older kids with their lessons and jump start your toddlers as soon as they can behave themselves at the piano.
It's a family project that really pays off and is often passed down through generations.