As I understand it, you are all meaning adding a layer to all layouts simultaneously. Such a feature surely should be a tick box of current layouts which therefore gives you the option of choosing multiple layouts to add a layer to (or removing one). Hence, perhaps "Add multiple layers" may be an even better name than "Layout familes" or "Global Layer". :P :P
On a side note, depending on your expertise, time available and if it is not a hassle. In a future game you may like to experiement with having much fewer layouts. But the 'main game' layout has the ability to load and run a map from stored data (i.e. an array). This normally requires a level editor (created by yourself), but has certain advantages with adding and updating levels and gameplay. But takes longer to set up. It all depends on the size of your game.