Hey Happy.
I switched the morning bottle a month after dropping the BT. Now for us it was vital the milk intake didn't drop because he still needed that milk (for us he has cheese but no yoghurt which for many LOs is an easy source of dairy across the day) which is why it took a month to switch. I tried several times to offer a straw or sippy cup in the morning but no go, he would get upset and not drink so after trying a few days and getting refusal (I would immediately pour it into a bottle and give him that) I waited another week then tried again. In reality a month isn't so long really but it felt longer.
I cut the bottle teats so it was a big hole, sat him upright on my knee to drink instead of baby cuddles, this got him used to a much faster drink and a different sort of mummy-closeness in the morning.
Then I popped a wide straw (the bendy type) into the bottle (removed the teat) and continued to sit him on my knee, holding the bottle and straw to prevent spills and giving a cuddle whilst he sat upright to drink. The straw offers a similar kind of sucking experience and kept his intake high.
I stayed with this method of the disposable bendy straw for a year. I switched the baby bottle for a grown up water bottle with the lid off so that I could finally chuck those baby bottles out. I also tried some other straw cups and bottles but I felt I couldn't clean the milk out of the straws so we stuck with disposable, I saved the used straws for craft activities so at least they were used again.
At around 2 we had a milk blip and he didn't want any...and when we came out of the blip he was taking morning milk in a sippy cup. We are still working on the open cup drinking skill.
Hope that helps some. I would work out the dairy intake across the day so you know how much she needs to maintain in the morning. For me I would have stayed with the bottle longer if ditching it meant too large a drop in milk because you can still brush teeth after this bottle so it isn't as bad as a BT one after brushing yk?
Good luck!
