I have a couple of suggestions:
Change your routine, I know it is hard but that is the best way for them. If you kind of throw off thier routine for a few days they will make a fast transition.
Make the bottles unavaliable.
Offer good foods and milk other times of the day, so that if they refuse the milk at dinner, they will have had the calories other times inthe day and won't miss them.
Ok, about changing routine. THe morning couple be milk in a sippy and when they ask for the bottles just remind them they are gone now. There will be some crying but it won't last more them a few mornings.
Making the bottles unavaliable. Pack them up, let the girls help and then you can do many things with them. If the girls know a baby they like, they can "give" them to that baby. Let them actually give them to the baby and that mommy and dispose of them how she sees fit. OR mail them to babies, if you take the girls to the post office, the post man will take the box, read your little note on the box that says please throw these away and the girls will think they helped babies of the world. Whatever you do, let the girls help and then make the bottle disappear. This will help you when they whine for them and it will help them make the transition.
Remember they are eatting solids and don't have a NEED for 2 bottles of milk a day any more. They will get their nutrition from other places and you may even find they eat more food because they aren't filling up on milk.
As far as changing this up at night, after bath time, don't go to the palce they would usually get thier bottles , instead try some different place inthe house, read a few stories, sing some nerw songs, brush teeth, have a snack on the kitchen floor on paper towels with sippy cups. Whatever you want , just do something different.
In less then one week, you will have made new habits for them and the bottles will be a distant memory. You can do this and they are ready, they are big girls now !