@CustomGT @mjolsen
I had some time to play with this. Two important steps that are critical.
1 - hikvision firmware above 5.5.0 requires you to enable onvif in network>advanced >integration protocol (user type can be media)
2 - Create an onvif user name and password that is the same as your http web interface password for the camera.
3 - in
blue iris camera properties >video>configuration for that camera, use the onvif user and password you created.
(I tested with a different user name that the cameras http interface).
4 - In blue iris camera properties settings general, select clone master. This is certainly necessary of you are cloning cameras, it may not be necessary if you are not, but wont hurt. If you are cloning then uncheck clone master on the other camera you are not using onvif to trigger.
If someone wants to put this info combined with the above posts into a
wiki we can post it. I tested this and it works with regular motion detection and line crossing. I am not at the location to test with face/intrusion etc.