Intermediate Fact Table

Hi,

I am writing a BI solution for a recruitment company. In their
business, the can be n number of participants from different
dimensions linked to the same fact record. For example, a client can
be sent the CV of 50 candidates. That's my first problem. My second
problem is the variety of dimension participant types for a given fact
record. This results in the need for nullable dimension FK's - which
I'm trying to avoid. For example, consider the following two business
events. In the first one, a candidate fills a job. Easy, we have a
record in the fact table where the fact table has the following
columns: DateKey, EventType, CandidateKey, VacancyKey. No nullable
columns, great. But there are other events that I want to store in
the fact table too. Let's go back to my first example: The client is
sent CV's of 50 candidates in one transaction. So there is one client
linked to the fact, but 50 candidates. So now I need to extend the
fact table and add another column: CandidateGroupKey (which links to
and Intermediate Fact Table). But in this case there was no vacancy
involved. So do I now have to make the VacancyKey column nullable?
That doesn't seem like a good idea...
Or do I have to go for a completely different approach and have
different fact tables instead of just one?

Anyone have any suggestions?