Importing two fem structures into COMSOL CAD

Hi all,

I am trying to import two fem structure variables into COMSOL CAD.
File>Import>FEM structure>Enter name of FEM structure variable>OK.

I had no problem to import each FEM structure into COMSOL CAD. However, it was impossible to import two fem structures into COMSOL simultaneously. For example, when I try to export the 2nd FEM structure, I need to save and close a current model that has the 1st FEM structure. Q> Can we import two FEM structures into a single COMSOL model?

In MATLAB Interface, I created my 1st and 2nd fem structures in the following way:
g1=geomcoerce('solid',{f1,b1});
g2=geomcoerce('solid',{f2,b2});
g12=g1*g2; % Intersection
fem1.geom=geomcsg(split(g12)); % The 1st FEM structure
g3=geomcoerce('solid',{f3,b3});
fem2.geom=geomcsg(split(g3)); % The 2nd FEM structure

Q> In MATLAB Interface, how can I combine two fem structures into one and import it to COMSOL? I tried the followings, but the result was unsuccessful.
g4=g1*g2+g3; % Intersection and Union
fem3.geom=geomcsg(split(g4));

Q> If it is impossible to do such a work in COMSOL GUI, how can I perform the work in MATLAB Interface environment?

Thank you very much for all your suggestions.

Evan