The TS005 document specifies a means to setup multicast sessions remotely. It supports up to four multicast sessions by specifying a Group ID with each command.
Class C can simultaneously receive unicast and multicast downlinks if the RxC multicast window parameters are identical to Rx2 (as unicast listens using Rx2). Also refer to 6 - Class C: Continuously Listening for Downlinks: Listen for Class C Downlinks | Semtech Learning Center. Thus, the device has to check two sets of session parameters when decrypting a packet.
TS005 does not specify what happens with multiple multicast sessions however. If they are configured with identical RxC parameters, must they be active simultaneously? TS005 does specify a start-time and timeout value for these multicast sessions, but does not mention anything about “stacking” sessions. Nor could I find such a reference in TS001 (looking at 1.0.4 and 1.1).
If anyone has experience or is able to find more on Google than I did, I’d be happy to hear from you 