So my local icecast server has many streams, bit I just want to forward 2 of them.  Unless I am missing something, this isn't possible, it's all mount points or just 1..

Have I missed something? If not, that seems like a crazy limitation.

if I understand you you'd like to push your stream to another server
That would be done with a relay, I broadcast my radio stations with icecast and relay a shoutcast stream on 1 server with multiple licenses

What are you trying to accomplish with forwarding?