I have a small workaround for this:
In Universe create:7 objects as:
objects name 0-2: in select '0-2'
3-5 : in select '3-5'
6-10: in select '6-10'
11-20: in select '11-20'
Now add new query to webi report and add one dimension that is unique at db that you can use for merge.
in this new query add combine query and add 7-8 combine queries.
In each combine queries: you can add dimension and the objects created say in combine query1: add d1 and 0-2 object
in combine query2: add d1 and 3-5 object.
Now use the 0-2 object created out of this query for your reporting.
Please give it a try and let me know how it goes.
Cheers,
Kiran