Kushies Infant Waterproof Wrap

I thought these all-in-one nappies with waterproof outer and flip-out, stuffable lining would be great - but I've been disappointed. Even with the washable liners, they always leak! They are supposedly suitable for 10-22 pound babies, but only when my babies hit 15 pounds did the nappies stop leaking around the legs, and they still leak around the tummy after just an hour or so of wear. They're also quite stiff and bulky around the waist, making sitting up even more tricky for new sitters.