If your engineers as self-satisfied about finding her as it sounds, then they'll be happy to describe their process over a beer or two. I've never known an engineer who doesn't like discussing how they solved some riddle.
The engineers were made to beg for info on the girl, so they might be getting some satisfaction from keeping a secret from the author in return. I know I would. Give 'em a taste of his own medicine. Also, if it was a relatively simple solution, it's probably more exciting with some mystery overlaying it rather than just explaining it outright.
If your engineers as self-satisfied about finding her as it sounds, then they'll be happy to describe their process over a beer or two. I've never known an engineer who doesn't like discussing how they solved some riddle.