Hi, Surya.
There is an old program called CTWind that I wrote when I was working with the coherent structures. It merges the FF files with the coherent turbulence and can generate FF files (I think). Here is a link, but I must warn you that I haven’t looked at this in many years.
FAST v8.12 has options to output wind speeds at many different points. In InflowWind you can specify wind velocity outputs at points fixed in space (wind.nrel.gov/nwtc/docs/AeroDyn_Manual.pdf).