PRV with a control node

How can I use a pressure reducing valve in the hydraulic model controlling the pressure at a control node? In water supply systems, we often automate valves to communicate with a critical point, instead of controlling the outlet pressure (pressure to, ppstream). But in WateGEMS only the pumps have this function. How do I keep a pressure fixed on a junction with a PRV? Considering that I have several scenarios with different demands, so using patterns is not a way.