Unfortunately I don't think this is possible. One client must connect with one set of credentials.
If you know of another technology that provides something like this please let us know and I can capture it as something of interest but it wouldn't be a priority to implement.
But maybe you can elaborate more on the issue and we can find a solution? Are the apps connecting to multiple messaging services/vpns and you only maintain some of them? Or do you have multiple people providing client access to the same vpn?