you can try changing the join to LEFt outer on the link in the Data Expert. that will get 1/2 the other 1/2 is to set a record filter in Report/Selection Formulas/Record or to add a where clause to the SQL...I haven't done this in a very long time. Perhaps DBlank can help.
My personal perference is to use stored procs. A bit more work up front, but they are way more flexible and these sort of issues don't arise.
Changing an existing report that binds to the data tables, or even another stored proc, to a stored proc is a bit frustrating, the first couple of times...but by then you hope you have a system, or that you never need to do that again ;)
HTH