Edit CollectionProperty of scene?

I have a script where I add a CollectionProperty to my scene to display a list of items in the interface. I want to be able to keep a few of these CollectionProperty elements separate from the scene and load them into the one linked to the scene when I want to display that certain list. It would look something like this:

bpy.types.Scene.mycp = bpy.props.CollectionProperty(
type= myList,
name= “My List”,
description= “”

Then I want to be able to do:

bpy.context.scene.mycp = theSelectedItemsCollectionProperty

However, Blender tells me the property is read-only. I tried adding a dynamic property (as explained here) but it seems a dynamic property can only refer to an existing attribute of the class you want to add it to, not create a new one.

Does anyone know of a way to solve this problem? I do not know the number of lists in advance, so it is not possible to just add a whole bunch of CollectionProperties.

afaik you have to add each item separately:

for item in theSelectedItemsCollectionPropery:
bpy.context.scene.mycp.add().name = item.name