Partial detachment is the desired regime for the baseline burning plasma scenario in ITER and next-step devices, as it allows to disspate the majority of the energy carried by charged particles through the scrape-off-layer (SOL) and thus avoids localised heat flux deposition in the divertor region. The COMPASS tokamak is equipped with an open divertor and has a relatively short connection length, both factors being unfavourable for access to detachment. As such, it only allows to approach naturally detached operation at very high line-averaged densities (> 1020 m-3), which are incompatible e.g. with maintaining the ELMy H-mode regime. In order to achieve the detachment at lower densities, impurities (such as nitrogen) should be injected into the plasma in the divertor region. A series of experiments with impurity injection in the range of 1-91020 molecules per second at different locations in the divertor were performed with the aim to cool the plasma and influence the particle and heat transport onto the divertor targets and provoke partial detachment. Previously reported results [M. Komm et al, EPS 2017, P1.118] were largely extended by injection of nitrogen at the outer divertor target. In order to analyze the divertor heat flux footprint in seeded plasmas, we introduce a buffered heat flux qB, which is approximated by an exponential decay.A new set of generic parameters – the peak heat flux qpeak, the fraction of power reaching the target fdiv and divertor footprint spreading factor Sf was proposed to characterise divertor footprint under detached conditions.