This week we learned the halachos of warming up a baby bottle on Shabbos, There are two very simple ways that are lechatchila. Number one to put the bottle in a kli sheini, or option two , one can pour from the urn directly onto the bottle because the contact from a pouring will only cook the first layer i.e. the plastic of the bottle and not the milk inside therefore this is a valid way to heat up the bottle. If one is very careful to pour a little hot water in the milk but you have to make sure that the milk will just warm up a bit but not reach level of cooking, this requires special attention to just pour a little bit of hot water in the bottle.