Convertible single and multi-seat stroller

A stroller device comprising at least two carriages connected together, wherein both carriages comprise:

• a support unit comprising a seat and a push handle connected to the seat,
• a wheels assembly rotatably coupled to the support unit, wherein the wheels assembly comprises two rear wheels and a frontal wheel axial structure on the front of the wheels assembly, wherein the frontal wheel axial structure comprises at least one front wheel, wherein each wheel is a swivel wheel capable of swiveling about a vertical axis and can be locked in four incremental 90 degree orientations the vertical axis;
• an engagement element for engaging the carriage to the other carriage of said at least two carriages, wherein the engagement element connects the carriages with the frontal wheel axial structures in a front to front position;
• a pivoting element coupled to the support unit allowing rotating the support unit, and
• a locking member capable of locking the support unit in perpendicular positions with respect to the wheels assembly, facilitating the support unit to be rotatably reoriented so as to allow transporting the stroller device such that the support unit of the carriage and the other support unit of the other carriage can be aligned in a train state wherein one of the carriages is behind the other carriage based upon the direction of motion of the stroller device and alternatively in a side-by-side state wherein where the seats are positioned in parallel to the direction of advancing with the handles behind each seat without disconnecting the carriages.