I never put DD1 on the top, only IN the big part and stuffed groceries around her. It didn't last long anyway b/c she hated the infant seat.
DD2 didn't like the infant seat either (what's with my kids?) and I had to get a RA by 3 months. She was in a carrier (BBjorn, Hotsling or Babyhawk) for most shopping trips!
It makes me cringe when I see a precariously perched seat on a cart. Esp with older sibs jumping around in the big area, they could dump the poor baby easily. I try not to do mommy drive-by's but sometimes it looks so dangerous I can't help myself!
Bodyboarding, music loving, clothing upcycler Mom to adult kid1, elementary kid2