How to determine the transmissivity of a system of rocks and faults from the stationary drawdown pattern?
I would suggest Bense (Hydrologische Karakterisering van Breukzones in Zuid-Oost Nederland), as a starting point. It provides a clear view of a few methods used in the past and an indication of the level of detail needed for the analysis, possibly helping you narrow down your search to a suitable method. Mostly Dutch (not a problem, judging by your name), but few international sources too.

I have attempted to ascertain something similar in a spatial model (MODFLOW) recently. From experience, I can tell you that the placement of measurement locations is vital, especially when estimating fault resistances. In my case, the available observations offered no evidence supporting the presence of a fault, even though upward seepage and indicator species were widely observed.