This is truly a mess. I originally purchased by Blink system due to its ability to integrate with SmartThings, but at this point I am too far in to switch to a different camera system. As a temporary workaround I devised a scheme that allows me to enable/disable the system, and exposes the cameras to SmartThings as motion detectors that I thought I would share. However, my setup is relatively basic compared to others I have seen mentioned in the thread so it will not work for everyone, but I thought I would share. My setup only requires arming and disarming the Blink system, and registering as a motion sensor in SHM. The solution does require IFTTT, which I was lucky enough to successfully link.
First, I created a virtual switch, and two corresponding IFTTT applets. One applet that arms the Blink system when the switch turns on, and one that disarms the system when the switch is turned off.
Next, I created a virtual device for each of my cameras using the universal device type from @Mike_Maxwell (linked below). The ‘virtual cameras’ were configured have a switch input, but output like a motion sensor, also to automatically turn off after 5-minutes. Each ‘virtual camera’ was linked to an IFTTT applet that turned the switch on when motion was detected, which registers in smart things an active motion sensor.
Hopefully this can help.