After the 1.4.5 update, the ability to turn on ONVIF becomes available (Shown below). This allows you to add the NVR to a 3rd party NVR.
Models confirmed....
ED9616H5NV-16P-A
1. Click Function panel
2. Click Network
3. Click Integration
4. Click the checkbox to enable ONVIF
5. Click ADD to make a user. For this part make the user "admin" and make the password the same as the device.
6. Click Apply