Since 4.10 is recommended to use a AI controller as provider of diplomacy options:
class AIMODULE_API AAIController : .... public IGenericTeamAgentInterface
Override method with logics of your game:
virtual FGenericTeamId GetGenericTeamId() const override { return TeamID; }
virtual ETeamAttitude::Type GetTeamAttitudeTowards(const AActor& Other) const override;