One thing at the time here!
First of all, B-C-N combination is already supported in 13.8, however not if you also include H, but that shouldn't be necessary anyway. See attached script - the BNC parameters are taken from the paper I referred to above, in fact.
For MoS2, I am not aware of the existence of any classical potential, but if someone knows one (fitting the types we have support for), we'll be happy to include it.