Two policies
Two policies can apply to one leak. The water does not care which.
This is not legal or insurance advice. In practice, corporations and unit owners often have different coverage. They both need the same physical facts.
Do not start with blame.
Start with where water originated and where it travelled. Responsibility language in bylaws is applied to those facts, not the other way around.
Give both sides the same record.
A finding that changes depending on who is in the room will be challenged. One dated note with photos and access limits is the useful product.
Ask your broker the coverage question.
Deductibles, betterments, and betterment exclusions are broker and corporation questions. A leak investigator should not pretend to interpret a policy.
Questions people ask
If the leak started in my suite, do I automatically pay?
Not something a website can decide. The corporation’s documents and the insurers decide after they have facts.
Should both insurers be notified?
Often yes, but follow the corporation’s process and your own broker. Do not wait on that debate while water is active.