Night time bottle!

Help and advice please!
I feel really silly for asking this, (especially on my third child) but I'm at a loss.
Our daughter is 18months old next month. She is our third child, with a 7 year gap.
Our first born stopped having a night time bottle at 16 months, I just gave him a sippy cup of milk of a night before bed and he was happy to give the bottle away.
Our second born stopped having a bottle as soon as she turned 1. The night of her party (family get together) I put her to bed without one and that was the end of it!
Our now 18 month old, will not give up her bottle! Absolutely refuses to go to sleep without one! I have tried the sippy cup, distraction, even a small milkshake before bed. And she flatly refuses to sleep without one.
Should I be enforcing the no bottle? And if so, how?
Or should I just let her be, and let her decide when to give it up?