A while back I wrote a post about how to combine measures from different facts in an OBIEE analysis. If you missed that then you can find it here. One of the key issues I highlighted was that generally it is only possible to join up facts where the dimensions you are using are common across both facts. I.e.
There is however a technique that can be used to achieve this. Let's assume we want to report on the number of sickness absence days by department in a BI Apps model. A simplified view of these two facts and the mandatory dimensions would be