A source inventory cannot currently be designated if it is in a region owned by more than one team. A system needs to be implemented where if a SourceInventory is designated ambiguously, the plugin asks the admin for more information (perhaps to respond with which team the SourceInventory belongs to).

Can't you give an error while setting up and ask the mapmaker to add an extra flag/region to those Inventorys and that can only be opened by that specific team