Trying To Use SSIS Variables Within SQL Queries Associated With Lookup

I'm trying to understand how to use SSIS variables within SQL commands and which Data Flow toolbox objects I can use for this. My simple package has a OLE DB Source object that returns the rows in a table. For the next operation, the output from the OLE DB Source is input into a Lookup data flow transformation where there is a select query that returns another value from a different table...

select bla from myTable where dbname = db_name()

The output is then passed on to an OLE DB Destination.

The above lookup query only works because, it so happens, that I could get a unique and correct result back filtered by current database name. However, due to other required changes, I now have introduce more 'where clauses'. I have all the necessary clause information in SSIS variables (iterated via a For Each loop). I would like do something like...

select bla from myTable where dbname = ? and bla_type = ?

However, there isn't a facility for Parameters in the Lookup object's 'use results of a SQL query'. I can see that I can use parameters in the OLE DB Source object by changing the 'data access mode' to SQL Query. However, it doesn't seem valid to join two OLE DB Source objects together in the data flow? I can't see any other suitable objects in the Data Flow toolbox. Ideally, I would be able to use Parameters in the Lookup object or some other object that would do the same job.

Thanks,
Clive