Difference between the observed and real α between 0.3 and 0.7 M_⊙ depending on the multiplicity for the last timestep of the main model (top) and the low-mass models (bottom). The data is colour-coded according to the real α (left) and the portion of T1 stars (right). Populations with a larger fraction of unresolved multiple systems thus have a larger Δα and therefore a smaller observed α, i.e. the observer deduces a flatter MF. The grey area shows the uncertainty in the slope. Note that for the five low-mass models, all data points are plotted and fitted together.