Okay, I'll take a scene based on the Playroom, but they all work in basically the same way. To make it non-overwriting, you need to choose an ID number for it which is different from the ID numbers in all the other scenes. Some ID numbers don't please the game, but for your first effort try something like hex 0340 -- so it will look like this
Also you can see that I've changed the Display Name to Flyeroom too. Choose a name of your own -- whatever the scene itself is to be called, that's what you want to put into the Display name and also into the first two names -- not the third! -- that you see under String List, 63 as shown here
If you do those things, the scene will show up in the Babyza scene drop-down list. .