Hello, I'm trying to use AHFinderDirect in the simulation of the NSs merger and was wondering if somebody can suggest how to set up the parameters for this thorn? More precisely I simulate two neutron stars tracked by moving grids. I can evolve this until merger and simulation fail once BH horizon has formed. I would like to use AHFinderDirect to look for a AH. Particularly I have a several questions: 1) Do I need 3 centres of refinement in order for AHFinder to work? By 3 centres I meant 2 moving grids and one stationary at the origin. (I just looked at qc0 parameter file as an example) 2) What's going to happen with a 2 moving grids when apparent horizon was formed? Since I use maximum density tracking mechanism to track the positions of the NSs I want to switch the moving grids off after the formation of the apparent horizon and have only one centre of refinement at the origin. I was wondering if somebody had an experience in this type of simulations and would be willing to share it. I would really appreciate any suggestions and help. Thank you.