The distributed nature of cell-free massive multipleinput multiple-output networks, where multiple access points serve users, offers an attractive opportunity to enhance security and enable physical-layer group key generation. However, usercentric operation introduces a key challenge: users observe different subsets of access points, leading to non-identical observations and potentially inconsistent group keys even when all users succeed. In this paper, we propose a receiver-aggregated, dealerless framework for group key generation in user-centric cell-free networks. The core idea is to exploit distributed access points as entropy contributors while enforcing consistency through a scheduler-defined common contributor pool, which aligns observations across users and enables consistent all-equal key agreement without direct user-equipment communication or centralized key assembly. We further address insider threats, where compromised access points may send authenticated yet inconsistent messages. By incorporating verifiable secret sharing, such behavior is converted into detectable erasures, preventing silent key divergence and enabling robust threshold reconstruction. Simulation results demonstrate reliable key agreement under heterogeneous connectivity, resilience to insider attacks, and high entropy at practical signal-to-noise ratio levels.