I have booked 3 rooms through CRO which includes our family, DH's sister's family and their parents. I requested two connecting rooms and the third room to be adjacent or across the hall. When making the reservation, they want the names of everyone in each room and you get a separate reservation number for each room. The deposit is due within a few weeks, so I paid my deposit when making the res and had my inlaws call in separately to pay for their room deposit with their credit card.
I was told by CRO that when you make the reservation together like this, they automatically put you together, as opposed to everyone calling separately to book. But I'm not sure if this is always the case or whether it's because we were given a Grand Gathering number as well as our reservation number, since we have over 8 people in our group.
Hope this helps.