Repeated references in footnotes

Hi, I am struggling with repeated references to the same source in footnotes.  I don’t want the reference to repeat all the details but just use the Author (Year) format for subsequent references.  I’ve figured out how to do this by editing my output style (which is Chicago 17th Footnote).

My problem comes when I have different sources with the same author and year.  I would like the repeated references to resolve this ambiguity using the convention of adding “a” then “b” after the year.  This option seems to be available for in-text citations but not for footnotes.

Is there a way I can do this in footnotes?

Many thanks!

I don’t think there are any footnote styles that use this mechanism, so I don’t believe it is an option, unless you use “same as citation” options in th footnotes, which obviously then requires a full bibliography.