Convertible Child Safety Seat Assembly and Method of Operating the Same

A convertible child safety seat assembly includes a seat portion and a removable seatback. The seat portion has a seat portion having an upper surface, and an elongated slot opened on the upper surface. The seatback is affixed with at least one beam that has an elongated shape. The beam has a distal end, and is assembled with a latch movable transversally relative to the beam. The seatback is attached to the seat portion with the beam received in the elongated slot, the distal end engaged under the upper surface, and the latch engaging through a sidewall of the elongated slot.