VirtualVP only supports 4 concurrent COM ports (so no more ports on that system once they're all in use), but it does support an additional 4 TCP/IP ports (for a total of 8 weather software programs you could be running).
If your new weather software supports TCP/IP connection, then use that, otherwise, you can switch one of the current COM port users to use TCP/IP instead and free up the old COM port for use by the new software.
I have VVP set to use COM ports (5 to 8 ) for WeatherLink, Weather-Display, VWS and Cumulus.
Then the first TCP port is used by Meteohub on the SheevaPlug. .. I still have 3 more TCP ports to play with.
BTW.. I've found that a second VVP running on a different PC on my local network can easily connect to the first VVP via TCP/IP and offer another 4 COM and 4 TCP ports for testing on the second system