Where scoping reveals that a critical in-scope system is actually managed by a separate internal team not yet consulted, good practice is to engage that team directly to confirm their awareness, gather their input on relevant risks or constraints, and secure any necessary sign-off before finalising scope covering that system - ensuring genuine, sufficiently authoritative agreement. Proceeding without their input (A) risks scoping decisions made without full relevant knowledge or authority, permanently excluding the system without further discussion (C) may unnecessarily narrow the engagement's value when the issue could likely be resolved through proper consultation, and assuming the original contact has full authority over every system in a large organisation (B) is often incorrect and risks the authorisation gaps discussed in the legal considerations domain.