I agree with Skybie, just give her the bottles for now (if you're comfortable doing that) and try cutting back when she's older and can understand better.

16 months was a trying time for us sleep wise with DD1, as was the lead up to the birth of our second daughter when DD1 was 26/27 months. DD1 had a horrible time cutting her eye teeth around 18 months too which certainly didn't help but I think that age is often trying when it comes to sleep anyway

When DD1 has sleep issues, we gave her small bottles throughout the night if she needed it and if we thought she'd has enough milk that night, she got water - which she hated but she quickly learnt we meant business. We just had to sit with DD when she was upset because she too wasn't a fan of co-sleeping at that age. It was hard yakka but eventually she came out the other side.

Before DD2 arrived, I was so stressed about how I'd cope with DD1's sleep issues and a newborn so DH gradually had to take over more and more both during the day and night. Ironically, DD1 coped absolutely fine when DD2 arrived and while I was in hospital and continued to sleep well when I returned home. She was a bit older than your DD but I think the lead up to a new sibling can often be worse for the older child than their actual arrival. Just offer your DD as much support as you can, as trying and tiring as it is.

Sorry, probably not much help but hopefully knowing that the horrid sleep issues do often resolve on their own will make you feel a little better.