Database Software

I've seen several queries in the forum that deal with multivalued dimensions. Sooner or later the "kimball" articles on "helper tables" or bridge tables are referenced, then the inevitable question .... "so how do I do a helper table in OWB" is asked.... but no one answers ... does that mean the answer is you can't have a help/bridge table in OWB?

I have an "organization" dimension, on some of my products the organizations share costs ... in the OLTP system that we're replacing this is handled similar to the "helper" table in that multiple cost records are assigned to the assets and the "weighted" value for each record has a validation to ensure they all sums to 1.

I think my options are:

1) force the dimension to have only one value (In my case this means change the business process which is not a valid solution)
2) Use a helper table (can't figure out if this is doable in OWB)
3) create a fact with multiple FKs back to the Organizations table (assumes a "fixed" number of multiple values for the dimension, don't really know what this upper limit is).

Any thoughts here would be appreciated.