pde – How can I add Interface boundary condition between two domains(geometry) in COMSOL?

Please see the attached image/problem[Interface coupled problem statement] below. It has two domains with two PDEs coupled at the interface. I have no problem solving two coupled PDEs for a single geometry, but for two different geometry, I am not sure how can I add two interfaces BCs at the interface of two domains in COMSOL. Can you give me an idea/useful links/example code of how to solve two PDEs in two domains in COMSOL coupled at the interface?

I need to find the variation of two variables(u1 and u2) along the x-axis(1D problem). If you need to know more about the problem,please let me know.

Regards,
Anadi

Interface coupled problem statement