K.L.
I'm not certain, but I think you're not supposed to run/jog with infants until they have good head control (too dangerous for them with all the bouncing before they can control their heads). So she wouldn't want joggers with the carseats anyway (maybe that's why it's hard to find them!) She should check with the pediatrician before jogging with the infants. I think you're right about waiting until they're appropriately safe for the 5-point harness!