When using Chicago style formatting, when needing nested parentheses one should use square brackets for the inner set, (see CMOS 6.101, in the 17th edition).
I typically edit the citation manually during writing; however, I will often need to update the bibliography. This requires me to go back and reformat the citations, which can result in missing some (and is generally a pain).
An easy solution would be to add to use square brackets in place of parenteses as an option near the “Suppress Author” checkbox in the add citation dialog.
I am using the Word plug-in for reference, but I believe this affects Google Docs IIRC.