Thank you for your reply. How are BGCs done, in a nutshell? (Sorry, I don't mean to play dumb - I have been reading a lot of conflicting opinions, and would genuinely like to know your take.)
1. You only need the PCCs where you no longer reside, the police certificate must have been issued after the last time the applicant stayed in that country for 6 months or more in a row. If you want to get a US PCC, you can do so, but is not required unless specifically requested by IRCC.
2. Your theory is baseless and this is not how BGCs are done.