Demand response (DR) is typically organized by higher-level (provincial) power grids, but these lack the capability to monitor the real-time operational status of lower-level county-level grids. Executing flexible resources according to plans may trigger localized security risks in subordinate grids. To address this issue, a multi-level security verification and correction method that accounts for the uncertainty in flexible resource (FR) responses is proposed. First, probabilistic modeling is applied to capture FR response uncertainty. Second, integrating voltage-power sensitivity and line transmission power sensitivity, a multi-level safety verification and correction model based on opportunity constraints is constructed. This model aims to maximize compliance with the response plan of higher-level grid. By fully accounting for response uncertainty, it ensures the operational safety of lower-level grids while maximizing the fulfillment of higher-level grid requirements. Finally, the validity of the proposed method is verified by simulations on IEEE 33-node distribution system.