Here, try this plugin.
It requires the
Server Comm API I made.
To set servers that share NVault data, add IP's (1 per line) in a file at:
addons/amxmodx/configs/remote_nvault_servers.ini
That file and code from plugin attached must be in all servers that will share the data.
Basically use the code from the attached plugin, and call the function
nvault_remote_set() to send data.
If you understand it enough, you would be able to write any other nvault functions you might want to use like get/remove/etc.