Country selection limited to single country per disaster event

[Byaxy]

Problem
The current form design only allows selection of one country per disaster event, but disasters frequently affect multiple countries simultaneously.

Impact

• Cannot accurately report cross-border disasters
• Incomplete event information for multi-country incidents

Expected Behavior
Users should be able to select multiple countries for a single disaster event when the disaster affects multiple nations.

[jacksono]

Involves a bit more work and needs further discussion on how we will show the different countries affected