One Word: WOOL
Since your girls have proven to be such heavy wetters, I'm scared to suggest any of the cute PUL covers I've seen but not tried. Posie Patch makes some, as does Sugar Plum Baby, but like I said, I haven't tried them, so I'm not going to recommend them :LOL.
You could peruse the trading post for a wool Bumpy and then take the kool-aid to it to make it cute

. Then there's always righteous baby, phunky mama, and any of the other WAHMs who have embroidery machines (or you could just buy me an embroidery machine and I'll make you lots of cute wool covers :LOL). I won't mention Fuz since we both know they're WAAAAYYYYY out of our price range!!
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