bass bridge

[Ed Carwithen]

I have an old upright with a bass bridge that has a sort of supporting
structure underneath the bridge.  This supporting part has separated, and I
am to work on it this coming saturday.  

If I take the bass strings loose so as to free the underlying bass bridge,
will the frame be put at jeopardy for cracking?

Should I loosen all strings before taking the bass strings loose?

I have worked on this piano several times for tuning, but the separated
bass bridge support causes a bad vibration in the A2 - D3 section of the
piano.  Something has to be done, but I don't want to make a bad situation
worse.

Thanks for your input...

Ed Carwithen
John Day, OR