A method for controlling a flow regulating valve (6) of a filling machine (1) forming composite packages (2) from a multilayer composite packaging material and filling the composite packages with a pourable filling product, wherein a position of the regulating valve controls the flow of the product filling the packages, the method envisages: implementing a flow feedback control, receiving a flow set point (F SP ) and an inlet flow measurement (F IN ) and generating a feedback control contribution (C FB ) indicative of a difference between the inlet flow measurement and the flow set point; implementing a flow feed-forward control, receiving the flow set point (F SP ) and generating a feedforward control contribution (C FF ) using fluid-dynamic maps, which map an output position of the regulating valve with respect to flow and pressure values of the filling product; generating a virtual pressure (Pv) based on the feedback control contribution (C FB ) generated at the output of the flow feedback control module, wherein the flow feedforward control receives the virtual pressure (Pv) and generates at its output the feedforward control contribution (C FF ) based on the flow set point (F SP ) and the virtual pressure (P V ) using the fluid-dynamic maps. The feedforward control contribution (C FF ) determines a control signal (S c ) for adjusting an operating position of the flow regulating valve (6).