Maybe if theres a way you can disguise the bottle? Using a cloth or something - or even one of your shirts that hasnt been washed - wrapping it around the bottle?????? Ive no idea to be honest.
My little girl is bottle fed. I gave her water out of a bottle when she was little, but once she was 6 months I switched to milk in bottle, water in cup. But thats not an easy thing to do in less than 24 hours.
Sorry I dont think I helped much.