From what I understand, that would depend on the order triggering the referendum. I would imagine that there would be discussions between the people from the various governments.
With the option that allows the use of various regimes, it would theoretically be possible to hold consultations in 10 provinces under 10 different systems. This is a matter that must be decided by the governments of the day. This option is always possible under the current Referendum Act, unless it is amended, as is the option of holding concurrent events.
As I already mentioned, that creates some administrative difficulties. A few cases have been sent to the Supreme Court of Canada. Voter eligibility is not the same under the federal legislation and under the Quebec legislation. Issues have been raised and they need to be clarified.