M.B.
Hi, my 22month daughter has been doing the same thing although not usually if she has poop. (She doesn't usually like yuckies so she only smeared her poop once) We tried the onesies for a while until she figured them out. Now we use duct tape and that works great. It is even hard for us to get off sometimes so I'm sure she can't get it off. She even reminds us to put it on her before she goes to bed! Good Luck!