Yes...that is the easiest way but unfortunately I rarely do things the easiest way

. I called a couple of weeks ago for BLT 1 bedroom SV for 6 nights on 12/3 - 12/9. There were only 1 or 2 rooms available on the 3rd and if I wanted to segment, I'd have to call back the next day to make my next segment stay. She said you have three options, book now for your 6 nights, call back each day for your segments, or wait the 6 days and then call back and hope all the days were available to then book and segment all at once. I obviously went went with an immediate booking so as to not lose the room.
She did say 1 VERY mportant thing...if you really wanted to segment, wait 6 days and then call back and ask to segement. She continued...whatever CM you get
DO NOT let them tell you they have to cancel your reservations to do it. She was adament with that. If you get a person who claims that, either hang up and then call back for a different cast member or ask to speak to a supervisor. She was very clear there is a way to segment after the reservations and even if there are no more rooms available. Most CMs don't like to do it she claims because it can take a while to get it done...especially on long reservations or if the person wants to break 10 days up into individual days....they really hate that one she claimed!!! It does take some time but they can do it (they have to call another group/person to help them do it).
So, I called the first time and got a CM who had no clue what I was talking about...I said thanks, will call back and have a magical day! I immediately called back and got a person who said sure we can do that. She then looked to see if there was availability...there wasn't so she said, "oh well, we will have to do this the hard way". She then asked for exactly how I wanted my 6 nights broken down (I told her 2/2/2) and she said well....3 is much better than 6! Anyway, she told she would have to put me on hold for up to 20 minutes as she had to call a different group/department to help segment the rooms and rebook so as to not lose the reservation. I said fine and about 17 minutes later she came back to tell me it was all done.
I immediately went to DVCMember and sure enough, my one reservations was now 3 but still tied together by the same reservation number. Sooooooo, this is a VERY long way of saying....call back and get a supervisor if the CM you get doesn't know what he/she is doing!
On a sidenote, there are still "issues" with how it is working and she did say we may have to go down on the day of the new segment to get new KTTW cards...I'd hope by December it would be fixed but then again...this is Disney IT we are talking about! I hope this helps.