Question / Help Create a base schema for using inside different scenes

[Fabbbio]

For my set up I use 3 or 4 web camera, 1 for scene , so I have 3 or 4 scenes with different point of view.
I want to create a logo and some overlays for using in all the scenes, but I don't want to add logo, advertise etc. in all the scenes.
I'm thinking about a master scene that overlay all the project., but how to do?
Thanks