N.S.
Try the Nuby sippers or something similar, with a silicone "nipple". That way the "sip" part is similar to a nipple and not hard.
Sounds like she likes to chew on soft things...maybe give her a teether?
Also, talk to her about the transition. She is 2 and will understand what you say. Keep it simple, and maybe let her know that the substitutes to the bottle will be at both homes.