Can I add a second child on the &Jog frame?Updated a year ago

No.  The &Jog frame was designed to accommodate one Switchback Seat, infant car seat or Bassinet.  

If your family needs a frame that can handle two seats, we recommend the &Roll frame.

As background, some parents purchase a typical 3-wheel "jogger" because they are perceived to be more all-terrain.  While that's generally true, our 4-wheel &Roll frame was specifically designed to be all-terrain with its various shock absorption characteristics and oversized tires, so unless you are fired up to jog or run, if you have or are expecting two kids, the &Roll frame may be a better option for you.