I have 3 bunnies, I've successfully trained one bunny of mine to drink from drinking bottle, but the others weren't able to do so. Do you think that success one could teach its friends to drink like the way she does? Like naturally? Or I should teach those two with the same method? Thank you.
I have a comment asking for clarification before addressing how to teach them to drink from the bottle.
From your description it sounds like the 3 rabbits are in separate areas. If that is the case I would not put them together so they can teach each other. Our existing question Introducing male rabbit to girl rabbit addresses some of the challenges on placing rabbits together. Even if they are sibling who have been separated for sometime, it can be bad. Rabbits are very territorial and are prone to fight each other when one is placed in the others territory.
Just take the bottle and hold it over their heads twice a for a minute every day and they will drink from it and eventually and they won't need you. I didn't even train mine they just noticed that their water was gone so they drank from the bottle. They will be fine because its instinct to get water.