post https://api.stg.mesta.xyz/v1/senders/ubo
Creates a new UBO (Ultimate Beneficial Owner) for a specific sender. Note: Document requirements (documentFront, documentBack) vary by country. Please refer to the validation-rules endpoint with ownerType='business' and the specific country to determine exact documentation requirements. Multiple UBOs can be added by calling this endpoint multiple times. The total ownership percentage across all UBOs should not exceed 100%."