Cross Subscriber Analysis

Hi,
I am working in a batch environment, receiving data and respectively refreashing our individual subscribers data-marts on monthly basis. We are planing to offer cross subscriber analysis

For the starter We built a master customer table from all the subscribers and perform the required analysis, it worked fine but for just 2 subscriber. Furthur this process involved alot manual query processing besides automated process.

We were considering to built a seperate data-mart for this analysis but this will mean that we are performing a union of all the dimensions and facts which doesn't seems to be good approach, any suggestions...