Read data from another cube's fact table

Hi All,

We are joining two cubes via a multiprovider. Cube 1 contains Suggested Retail $, Promotion Flag, Store, Article, UPC. Cube 2 contains Sales $, Store, Article, UPC, and we are adding Promotion Flag.

The problem is that the Promotion Flag in Cube 2, needs to be populated by looking up the Store/Article/UPC combination.

Cube 1 is loaded weekly, for the upcoming week. Cube 2 is loaded daily.

I was going to create some code in the update rules for the Promotion Flag field in Cube 2. This code would read the fact table for Cube 1 (where Promotion Flag is already populated) and then populate Promotion Flag (in cube 2). Problem is that the fact table is all based on dimension keys, not the characteristic values.

Any suggestions on how I might read data from another cube's fact table?

Thanks

Charla