Yes, there are two possible solutions.
Third possibility: Make a softlink that points to the new location.
Assuming that you have moved Bitcoin Core's stuff from ~/Library/Application Support/Bitcoin to /Volumes/Blockchain/Core, do this in a Terminal
cd Library/Application\ Support
mv Bitcoin Bitcoin.old
ln -s /Volumes/Blockchain/Core Bitcoin
ls -ld Bitcoin*
The last line should produce output like this:
drwxrwxr-x+ 14 username staff 476 Nov 11 18:01 Bitcoin.old
lrwxr-xr-x 1 username staff 43 Nov 30 13:10 Bitcoin -> /Volumes/Blockchain/Core
Now any program looking for the bitcoin data in the usual place will find it.