No one can tell you for sure what your individual chickens (they each have their own personality), with your flock make-up, with your management techniques, and with your facilities will do. As you can tell from these stories different things can happen. Some may split off on their own or you may have to train some to sleep in the other coop. Sometimes they stay trained, sometimes they don't.Would we need to somehow encourage some of them to abandon the old coop and go to the new coop or will they figure it out on their own?
I have multiple coops during the growing season, when my flock grows from one rooster and 6 to 8 hens in one coop to over 50 chickens, most growing to butcher size. I train them as to which coops to sleep in. They usually stick with the coops they are trained to but occasionally will spontaneously change, usually to join the main flock in the main coop. Usually I have to retrain them to the main coop.
Are you having problems because of overcrowding or is this something you anticipate happening, maybe as chicks mature or due to winter coming? I tend to not fix a problem unless I have a problem but I do anticipate and prepare for some things. I don't know enough about why you are considering this to give any specific thoughts or recommendations as to possible alternatives.