multicast sockets on multiple NIC's

I need to be able to join a multicast group on a specific ethernet device when more than one NIC is installed in the box. In LINUX you first have to find the device index, then pretty much just join the group with the index as an attribute to the usual POSIX socket calls.

I’m clueless on how QNX handles this. Does anyone know how, or perhaps know where I might find further resources to help me figure it out?

Many thanks!