setting solution to zero in subdomain

Hello! I am using the pdetoolbox to solve a N=5 pde system. I would like to have the last two equations of the system not included in the calculation within a certain subdomain. For this reason I would like to set the solution u(4)=0 and u(5)=0 in this subdomain. Is there a way I can set this? I could not find information in the documentation.

I have tried setting the coefficients m,d,c,a,f equal zero for the last two equations, but then the code gives errors.

Any help is appreciated!