Does anyone know if there is such a thing as a special needs trike with similar features to a smart trike or Doona liki for sen children? My son is coming up to his 4th birthday and loves watching his older sister on bikes and scooters but he can't pedal and would need me to steer and push and would need somewhere away from the wheels to rest his feet (preferably with ankle straps) he would also need the X shaped chest harness. Any ideas if something like this exists? TIA!