I am making a change to a specific PL/SQL function for a specific discoverer report, I have a feeling that this PL/SQL function is called by other reports as well, I want to know what the impact is (regression testing) on other reports but not sure how to identify other discoverer reports which have a dependency on this PL/SQL function.
You can try this one :
from eul10g_us.eul5_documents d,
where x.ex_from_type = 'DOC'
and x.ex_from_id = d.doc_id
and x.ex_to_id = e.exp_id
and e.it_obj_id = o.bol_obj_id(+)
and o.bol_ba_id = b.ba_id(+)
the other problem you'll get is that if you do find other workbooks you'll need to know whether they are in use or not.
hope it helped