A mixing subassembly for an exhaust gas system of an internal combustion engine for mixing exhaust gas, which is discharged by an internal combustion engine, with reactant includes a mixing path which extends in the direction of a mixing path longitudinal axis and which has an upstream mixing path inflow region for receiving exhaust gas and/or reactant in the mixing path. The mixing path includes a core flow channel, through which a first exhaust gas partial flow flows, and a bypass flow channel, through which a second exhaust gas partial flow flows. At least one flow blocking element reduces a flow cross section of the bypass flow channel and is arranged in the bypass flow channel.