H.B.
Hi, From my experience with second children (I have two boys, now 14 and 10), the second one will do whatever it takes to compete with the first one. Even at this young age. Give her a sippy cup (with handles) and see if she likes it. My youngest gave up the bottle around this time. I think it was because we always ate as a family and he could see his older brother using a sippy cup. Good Luck!