Control of the detachment front between the target and the X-point is necessary for minimizing the effect of detachment on the core plasma (core radiation and loss of confinement) and maximizing the divertor functions (reduction of target heat load and sputtering, He pumping). However, such control has been difficult in experiments. The SOLPS-ITER code has been utilised to study the issue for MAST-U Super-X plasmas where detachment is achieved through two separate scans of ‘control’ parameters – outboard upstream density (nu) and the divertor impurity concentration (fI). We find for either nu or fI scans that initially, as in current tokamaks, the detachment front moves quickly away from the target after detachment onset. However, in the Super-X geometry studied here, the sensitivity of detachment front location (in a normalised parallel space), zf, to the controls drops significantly in a region of high parallel gradients in the total magnetic field in the divertor. A simplified analytical model of the sensitivity of the detachment front movement to controls including nu and fI has been generalised to obtain zf for an arbitrary divertor total magnetic field profile and applied to the case studied here. We find that the model approximates the SOLPS results for both scans – a significant drop in the sensitivity of the front location to is predicted in a region of high parallel gradients in the total magnetic field. However, it is found that the significant drop in sensitivity in parallel space translates to a relatively mild reduction in sensitivity in poloidal space. Such slowing down and/or stopping of the detachment movement, if further substantiated, could provide a route to much improved control and the potential to passively stabilizing the detachment location in the strong region for a wide range of core plasma transients.