How I Combine two SSAS Cube In one Cube?

Hi Everyone,

I have devlop ssas cube using 20 dimetions & 2 Mesures. When I developed with Only one mesure group it taks to execute the process 16 min. when I add secong mesure group & run it it gives 29 min somthing. we need to develop cube fo multiple mesures groups so i want to add more than 2 measure  groups but when i use 2 mesures it taks 29 min so if again i add any more than two it tkas losts of time to execute. please let me know anyanother way to decrease the time of execution process for ssas cube.

i am thinkin as different way as : (please tell me it is possible or not)

If i design different cubes for all mesures group and add one more to add the new liked dimentions & New linked dimentions like creating Bridge if it it possible then it works as if i heat on one perticlar mesure then we use the process for only for this not to thers. if it works then it is very time consumtion.I will try but i doesnt get any ans currently..if you all know then please tell me

How I Combine two SSAS Cube In one Cube?
thank you.

--Parikshit