Suggestions on incorporating a metric to a BOBJ solution?

Need suggestions on incorporating the following Business logic as a BOBJ solution via IDT and WEBI:

Basic Business Scenario:

Every Prospect can visit multiple storage spaces.

Each storage space has a Square footage associated.

Requirement:

Now I need to report total Square footage for each month. To sum the Square footage, we need to consider the Space with the highest Square footage of all that the prospect has visited.

So I have a SQL like below from the above requirement:

Select Max(SqFootage) FROM ABC

WHERE MonthYear = "July 2014"

group By Prospect_ID

This will give me a Prospect wise Max Square footage. Can anyone help me understand how do I Sum these Prospect-wise SqFt and do this in BOBJ?

All I need on my WEBI is something like below:

Column 1: Month-Year,

Column 2: Total Square footage (for Unique prospects - Get the MAX sq footage if the Prospect has visited multiple spaces)

Your suggestions on the approacch would be appreciated.

Thanks,

RCC