This falls way outside what could be considered something that would be supported for free.
Even with commercial support you only get support 18 months back.
BK 4.1 is around 10 years old:
$ bk changes -rbk-4.1
ChangeSet@1.1875.1.3, 2007-10-12 15:19:13-07:00, firstname.lastname@example.org
This is a classic example of why you might want commercial support, this is not something
that any organization can be expected to do for free.
For anyone following around, this is coming from one of our larger customers who have
decided to go with the free version of BK (they no longer have any commercial seats).
Which is fine. Expecting commercial support for free is not so fine. I've looked at
the problem and it's non-trivial to fix (and most likely would not be a problem if they
had upgraded as we did releases).