sounds like the simplest solution is to create a stored procedure that will combine the data that you need into 1 table with all the information that is required. Adding data from a subreport, if it is just a total is not hard, but if you want to 'move' the data, this could be more complex...all depends on how your data looks and where you run the subreport.
to be fair, all my solutions usually start with use a stored proc...they are way more versatile than what CR allows with just joining tables together.