Best practice to display control boundaries

[Mistadouf]

In Canada, we have some areas of an FIR that are controlled by another FIR's ACC. E.g. Montreal covers parts of Toronto. Moncton covers a part of Montreal. Edmonton covers parts of Winnipeg and Toronto.
What would be the best practice to show pilots who they have to contact in these delegated areas, as they aren't necessarily from SFC-FL600?

I'm asking this because you mention that:

Included Sectors
To keep the map clear and not too cluttered, any new additions to the dataset should cover whole FIR's (e.g. HECC/KZFW). Some exceptions can be made for further splits if the (sub)sector is controlled consistently outside of events and the amount of traffic justifies it. This will be reviewed on a case by case basis.

[Mistadouf]