Help with multi security cameras/DVR with one IP online viewing

[Ghost101]

Ok, so I have an 8CH DVR from Zmodo that is currently active at my warehouse, I bought two other 4CH DVR from Raysharp to be placed in the warehouses accross the street. My cameras are set up in a business park we rent and each unit is close but not enough to run the cables (parking lot/road distance).

I have internet access in my main warehouse with wifi, and the other two smaller warehouses get the internet signal from the Wifi in te main ware house. What my question is, I have 3 active DVRs running due to location...and one IP address. My Zmodo cameras were bought a few months before the raysharp and I have them running and can view online. The thing is, how do I connect the other two Raysharp DVRs to the IP if the IP is already set to the Zmodo? I am scared to set the IP on them incase it messes up my viewing of the Zmodo cameras. How can I get 3 DVRs to work on one IP? When I enter my IP in a web address bar I get the Zmodo camera login. If I do the Raysharp I feel like it would cancel out the Zmodo. And if it doesnt still the login for Raysharp or Zmodo would need to be displayed. What do I do to get the cameras online with one IP address and two brands?