Captured image as image target or swap webcam at runtime

Hello.

I'm currently exploring a few solutions for an arts installation and wondering if VUFORIA is the way to go. We want to have 3 scanning stations with webcams to capture drawings that have AR enabled stickers on them and then apply this captured image as a texture to a pre-animated object. I'm okay with  the capturing part but I'm thinking is there a way for unity to track the saved image in the game world? So initialise not on the live feed but on the capture image texture.

 For example, if I have a scanned image that has an AR image target on it and I animate the scanned image to move across the screen, is there a way to use this as an image target and apply the AR content in the game world.

Alternatively, is there a way to use three webcams with Vuforia, so I can switch between each webcam source either on a timer or with a button on each station? 

Hope that makes sense. Any advice would be greatly appreciated!

Darius