Yea, it might be a pain moving all that stuff, but you just can’t call multicast functions on PlayerController.
Like GarnerP57 said, you could use all replicated variables and use OnRep_ functions to execute code when a replicated variable changes, but you would probably have to change a lot of what you’ve done already.
Here’s a thread that explains the difference between OnRep and Multicast.
However I found the OnRep stuff to be a giant pain in the butt for a bunch of different reasons.