Fuzzing a target that takes multiple files as inputs

[Mikerah]

I have a target that I've compiled with hfuzz-g++ that takes 4 files as input target file1 file2 file3 file4.
I've tried passing these files using -s and even tried putting them into a single file and using ___FILE___.
However, I'm unable to make the program crash.

Is this mode possible with honggfuzz, if not, are there any tips for making this work?