We just went with the flow with the dummy - had many trips to baby's room in the night to 'recork' her if it fell out. That dummy was critical to our sanity for a long long time.

However, she just stopped using it on her own when she was around 1, I think. We didn't actually do anything. We were worried she'd still be using it when she was 15 or something but it seems that worry was unfounded

New baby refuses dummies point blank. We bought one for him so DD#2 tries to give it to him, fails, and then briefly sticks it in her own mouth