Borrowing from @JasonWalker, “It Depends” ™
BFI uses built in automated bundling rules to assign the discovered components to products from the software catalog. You (or someone in the Software Asset Manager role) will need to use the UI to confirm whether these default assignments are valid in your environment.
In the scenario you are asking about, if MQ were installed on the same server as DB2, and you had uploaded the DB2 Enterprise Server Edition part number into BFI, then it is likely that the component MQ would be assigned to the product DB2 automatically, and would not be reported as a product itself.
In the Software Classification report, you would see something like this:
[ ] Pub ...| Comp ... | Comp ...| Product Name | Metric | Comp...
[ ] IBM | IBM MQ | 9.2 | IBM DB2 Enterprise Server Edition | PVU | server1
If the data shown on this row is valid, then you just need to select the row, and use the
Confirm menu entry to complete the assignment of MQ to DB2.
If you see something else, then the automated bundling rules were ineffective, and you will need to manually assign the MQ component to the DB product using the
Assign -> Choose from Catalog dialog to locate the proper product for this component.
In the final analysis, it is up to you to verify that the discovered software components are assigned to their correct products based on how they were deployed in your environment.