As Vicki said nothing is guaranteed. But having said that, we have gotten connecting rooms at CBR every time we've requested them and that was during peak times between Christmas and New Years. Good luck!
The great majority of guests who request connecting rooms get them, but Disney does not guarantee that any request will be met.
If having everyone together is an absolute requirement, the only way to assure that is to get a room that holds your entire group, such as a family suite, cabin or villa.