Convert nvr 4 to nvr 8?

I own a 4 channel Zmodo nvr for my 4 wireless Zmodo cameras. I now want to add more wireless cameras to it. Is it possible to convert a 4 camera Zmodo wireless nvr to show 6 cameras?
If not, what is the cost of purchasing just the 8 camera capable nvr (without cameras).
Thank you.

4 Channel NVRs are limited to the 4 channels, you can add more cameras on the app but they will not record on the NVR.
Check amazon, the 8 channel NVR Kit with cameras is pretty affordable nowadays. I payed $499 for the 8 Channel a year ago and now it runs for about $250. Hope it helps.

Thak you.I appreciate the help