Hi!
Yes, currently if you start a play session - you won't be able to add addons/mods to running session. However, we working on the fix allowing you to add mods to an existing GM session. This will be added in later patches.
Good to hear that part is in the works. What about adding more scenes? Planning on running a long term campaign and it would be hard to plan for everyrhing the pkayers might do and you can't sokit it into different campaignt due to no character export.
Do you just load up the campaign like you ate playing without the players logged in to keep adding scenes?