I know what you mean. Having them all in order then get a couple of new ones and having to shift every down to allow for a few more spaces. We started out with a Sony 300 disk player and then had to add a 400 disc player and now getting ready to buy another 400 disc (including blu-ray) player. The new one will probably be blu-ray only. When we started with the 300 disc unit we thought, what if someone broke in and stole the player full of new discs, so we started to make copies of the disc and put the copies in the Sony players and the originals are kept in a secure closet.
I don't know how someone could steal a 400 disc player because it is extremely heavy.
Or have a dedicated computer with about 10TB of total hard drive space.