We gave the girls some fun treat with raisins in it and one will grab one and the chase game is on. even know there are many more, its a big game of keep away.
I'm not sure which nipples you have but i bought a 'tap' to drill for the correct size of the nipple . put a dab of silicone on the threads and screwed them in and haven't had a drip. Here are the nipples i use.