Creating the right family object

There's no way to specify the object created from a family but also you don't need to make a condition for every sprite object, you could do something like create map object by name where the map you want is an instance variable on the sprite.

You can set the variable on the sprite as it's created and before you spawn the map if you put the events in the correct order.

But if you have to put the variable in the sprite variable as it's created isn't that the same amount of work as creating the normalmap individually when the sprite is created? You have to give each object its individual normalmap variable after all..

Yep. You didn't mention the sprites are created in original post, you said for each sprite it creates a map.

Yes, I think I might find it useful to also create them automatically when I create the sprites later.

One option of course is to have one object of every type placed in the editor (as you should do anyway since it helps construct load the objects you need in the startup) and have the string data saved in that object, so all the objects that get created after that will use that object's variable data as default. After that you can put those objects in a family "DestroyAtStart" and destroy them in layout start, and it apparently won't affect the objects' default variable data when created later on.