Can a fading channel with multiple modulation schemes be implemented in simulink and simevents?

I have a fading channel scenario that I am having trouble solving. I want to model a communication channel with a two different modulation schemes, BPSK and QPSK and a fading channel. For example, the QPSK modulation is the default modulation, but if the SNR of the channel reaches a certain threshold, then it should automatically change the modulation to BPSK in 'real-time'. Is it possible to create a fading channel with changing SNR in Simevents using the AWGN block (or some other block)? And if so, how would you implement a feedback to then switch between the modulation schemes while the simulation is running based on a SNR threshold? My current system is implemented in Simulink, but I also have access to Simevents if necessary.