Here is one approach (there are others), with simple examples tf's for C, F, and G, that you should be able to adapt to your problem.
The trick is to replicate F so that it has two outputs. One output to add to G and the other to keep as the output of the closed loop system.
E = parallel(Fnew,G,1,1,2,1);
ClosedLoop = feedback(H,1,1,2,-1)
ClosedLoop = minreal(ClosedLoop)