Mathematical model built upon modal identification from the force response function (FRF)

Hi there, so I have a structural-acoustic FEM model with complicated geometric configuration. What I would like to do is to design the active feedback control for vibro-acoustic optimization of the structure. Since the development of mathematical model of the whole coupled system for control purposes would be nearly impossible, I plan to build the simplified mathematical model. The idea is to compute the force response function (FRF) at several locations on the structure surface over the frequency band of interest. Then, an ordinary differential equation (ODE) based model is expected to be identified from these FRFs to represent the actual FEM described system. Feedback control design can then be performed within the ODE framework. I know my approach is pretty much like the experimental or operational modal analysis but I got kinda stuck at the point of how to turn the identified parameters into a well-suited ODE model? Meantime, are there any good matlab toolboxes for modal identification via FRF? Anyone who offers hints, suggestions, comments is greatly appreciated. Have a good day guys!