Citizenship by descent, but family won't give consent to obtain necessary documents.

I am eligible for citizenship via my paternal grandmother, however my parent's recent divorce has thrown a wrench into the works. I've already collected most of the necessary documents over the past few years, but I am missing my grandmother's naturalization certificate to the US. Currently I can't obtain her consent for a FOIA request, so I am stuck contacting local court archives trying to find the document.

Has anyone else dealt with something similar and if so how did you tackle the issue. Is there a possible work around or am I stuck?