While I'm actually have the opposite problem, queue_free is *supposed* to dump the previously loaded scene.
What you want is to merge your scenes together into one bigger tree.
I suggest create another scene (the trunk!), and which loads your other 10 into itself. You can do this in the Scene panel in Godot, or you can load it with script code with
onready var scene_loader = preload("res://OneOfYourTenScenes.tscn")
var s = sceneloader.instance()
if you are running a Node2D setup, you can shuffle the z_index to flip the one you want to the front.
If you are running a Spacial setup, I would just move the camera to the one you want to work with.