How to get total for all members based on property?

Dear BPC Experts,

I am looking for a solution on the following problem.

Suppose I have 100 base level members in my product dimension and I have 1 property named as "OPD" in it.

Now this OPD property has 2 values namely "A" and "B".

A value is attached to 35 members in the dimension.

Now I am building 1 report where, I want total of all base members whose property is either A or B.

I tried using member property function in different ways, but every time it gave me list of all those members instead of 1 line value for all the members.

Can somebody help me please?

Best Regards,

Ashwin.