Hi,
About the workflow that you mentioned, is the camera adapter doing some multiplexing or is it creating 4 separate camera interface within Raspberry Pi like /dev/video0, /dev/video1 and so on?
If it is multiplexing, you might have to control it via GPIO pins, like set the GPIO pins to 00 and take first camera's snapshot then change GPIO to 01 and then the second camera's snapshot and so on.
If it is creating separate interfaces you can create multiple webcam objects and then access the data.
In the past, people have faced problems using multiple cameras with a single Raspberry Pi. This forum mentions a lot of different workflows you could try. Please note, I can't say it will work, but it may be a place to start.