I have not a look into dlraw source, so my assumptions are based on your short explanation.
It looks like you have own postprocessing pipeline, different from dcraws. I guess, you may use LibRaw's as RAW reading tool (open_file() and unpack() calls), then switch to own processing pipeline.
Licensing is not a problem: LibRaw is licensed under LGPL ('upgradeable' to your GPL3), demosaic-pack-GPL2 is licensed under GPL2+ (also no problem) and AMaZE is licensed under GPL3, no problem too.
I have not a look into dlraw source, so my assumptions are based on your short explanation.
It looks like you have own postprocessing pipeline, different from dcraws. I guess, you may use LibRaw's as RAW reading tool (open_file() and unpack() calls), then switch to own processing pipeline.
Licensing is not a problem: LibRaw is licensed under LGPL ('upgradeable' to your GPL3), demosaic-pack-GPL2 is licensed under GPL2+ (also no problem) and AMaZE is licensed under GPL3, no problem too.