With a pup of this age and a young child you really should be supervising them 100% of the time, if you can't supervise you need to have the pup somewhere where she can't get into trouble. That way she won't learn to do the things you don't want in the first place. This is a lot easier than trying to train her out of something thats very rewarding :) Can you put her in a large crate or in the kitchen behind a baby gate when you are unable to supervise her? (the pup that is ;) )
Another thing you can try is when she picks up something she shouldn't DON'T CHASE!! as you have found this is way too much fun for the pup and not very effective :D Try enticing her with a toy and swap it for what she is carrying, or keep her favourite tiny treats in your pocket and 'swap' them for what she's got. My pup at the moment is 'retrieving' EVERYTHING and not a retrieving breed

but this is the best game in the world, pup 'finds' something on the floor and brings it to me, I say "Taaaaaa" and she sits and gets a treat/fuss/game :D so she's learning to retrieve and finding all the paper tissues my little one drops for me :D Downside of this is things get knocked off the coffee table to be 'found' as well LOL :D :D but they're never chewed, and always brought straight to me :D :D