My 15mo is heading in the same direction, she stands up in the trolley seat even when clipped in so for now she stands in the trolley compartment, she is fine with dd1 in their too but when it's just her she tries climbing out. I think I will just have to let her walk. Have you thought about one of those harnesses you strap on to them with a lead? I always thought they were awful but with no 3 on the way I am thinking of ways to contain dd2