Prototypes B-C of the seat assembly not only offer a simple and reliable solution for transitioning from a passenger seat to a child seat but also help save on the expenses related to purchasing different types of child seats. Furthermore, by integrating the child seat into the seat itself, it allows for space-saving in the vehicle's trunk. The child seat can be equipped with sensors to monitor the presence of the child and detect any impacts. The vehicle may also include an image acquisition system and an electronic unit to monitor the child and alert the driver or a rescue network in case of danger.