how to run nvr to a dvr

Not the way they work.

Possibly you could maybe bring both systems into Blue Iris if those systems are not proprietary.
 
how do you run a szsinocam nvr to a zosi DVR???? and only watch cameras on the dvr and not nvr ???
plug the WAN of the Szsinocam into one of the zosi 's camera port. Then add the cameras in the Zosi.

I notice Szsinocam is running a http site. Which might be an indication they have their TLS certificates revoked. So I will recommend you regenerating the certificates in all of that equipment.