Evoko Room Manager dual booking sources

Hi All,

Have a client that currently uses Office 365 / Exchange for booking conference rooms with LISO panels.
Now the rooms will be shared with an additional organization. They also use Office 365 / Exchange.
Cannot find a way to direct the Evoko Room Manager to 2 different Office 365 Exchanges.

Questions:
Any idea how to use 3 different booking Office 365 Exchange (domains) for the same LISE panels in the most efficient way?
Do we need Office 365 licenses for each room? We now added 8 more meeting rooms.

Thanks for any hints and help,
Robert