Two multi-selector valves were integrated into the setup to increase control for reaction monitoring or screening purposes, allowing for switching between several different microreactor positions during individual pre-programmed runs. This configuration enables easy integration of multiple packed-bed microreactors in parallel. In addition, a blank capillary was added at the first position, which facilitates acquiring blank measurements of the reactant feed or sole pump feed while bypassing the reactor. Furthermore, by switching off the reactant feed, reactor positions can be flushed between runs, and the efficiency of the washing process can be monitored. An initial validation run using a single connected packed-bed microreactor and a blank capillary is described in the ESI in Section S5.2. A constant reactant feed was provided for that run and then directed to the two reactor positions. Monitoring the signals during reactor switching, the flow behaviour was investigated and validated that no carry-over effects were present.