Electrification of transport and heat concentrates new stress in the distribution grid, while the same controllable assets constitute a flexibility resource. Activating that resource on a price signal alone, however, does not guarantee a feasible grid state, and the market-based procurement framework foreseen by §14c of the German Energy Industry Act is not yet operational. This paper presents the Orchestrator, an automated decision tool that evaluates standardised FlexOffers submitted by a neighbourhood from the perspective of a distribution system operator, weighing grid feasibility, established from an AC power flow of the CIGRE European medium-voltage benchmark network, against wholesale price, local peak shaving and renewable availability. The grid criterion uses feeder-specific warning thresholds and a materiality test, so that it responds to the effect of an activation rather than to upstream conditions. A low-voltage neighbourhood simulation and the medium-voltage grid calculation are coupled exclusively over MQTT. Over nine simulated months, 17.6 % of valid offers are accepted, with the two directions activated at systematically different times of day. Grid effects are measurable only in the immediate vicinity of the connection point, which quantifies the scale at which neighbourhood flexibility becomes visible to a medium-voltage feeder.