Left panel: two partially overlapping 4MOST fields with low-resolution (blue) and high-resolution (red) spectrograph fibres at their home positions. Right panel: patrol areas of high-resolution spectrograph fibres and four targets in a zoom in region highlighted in left-hand panel. Fibre home positions are marked as points and labelled with fibre numbers. Possible fibre-target pairs are illustrated with lines. Targets T2 and T3 can be reached by fibres from two fields; target T3 can be reached by three fibres from Field 1 and two fibres from Field 2; fibre 2313 can reach two targets (T2 and T3). Section 2.2 and Eq. (1) define the probability p_{tar, field, fib} for each fibre-target pair.