You also have to prove that there was a clear and overriding error in the application of the law; they seem to be applying the law appropriately in giving you a chance to respond to concerns.
@espresso87 you're jumping from what should be "let's gather everything with our addresses on it, including bills, Amazon packages, etc to prove we live together" well past the reasonable point to "Can we just get married and re-apply?" You really should focus on the question in front of you. This request, as a common-law application, is very common and most people respond with letters from family, friends, landlords, bills, packages bills of lading, and other things to prove they live together. Instead, you're jumping to the Federal Court.
There is a
public policy that says that IRCC will generally not deport someone solely for being out of status while a PR spousal application is in process, but that is not a law and people can still be removed (for criminality and other things). If you withdraw your application and re-apply as married, you are no longer in any sense protected by this public policy and your partner can be removed if CBSA wants to. Same if you're denied.
Focus on getting everything you can with your address on it. Notarized letters from your father. Everything you can and scan it in and send it. The issue may disappear silently.