information across different models

hi just wondering how to combine data from 2 or more data models and combine them into 1 report?
such like in a retail chain: one model has a transaction fact table contain store-seller-item-transaction level data. another periodic fact table contain which seller works what store each day. if you want to analysis average sells per employee, then you need to fetch data from 2 models, how to merge those information?
or you have a model schema contains the customers' feedback for each store and seller, and you want to link the feedback with store and seller's performance like total sells last year or average sell per month. how should you design the sell star model and survey model? how to fetch data from different models and put them in ad hoc report and BI tools?

thanks
howard