We present a method for identification of magnetic mirror structures (MMS) in multi-point spacecraft measurements and for deriving their full 3D geometry. Multiple minima in magnetic field data are no longer regarded as separate MMS but as belonging to the same mirror structure. The approach is based on fitting a model magnetic field to measured data from one or many spacecraft. Because of the complexity of the model magnetic field, fitting the data from only one spacecraft has proved not to be reliable even if data from the others spacecraft can be used for checking the results. The main reason is the instability of the numerical fit and the non-uniqueness of the solution found. However, performing the fit on the data from multiple spacecraft allow the use of information from different regions of the structure eliminating false results and improving the numerical stability of the fit.