I'm trying to set up a template for the Monumenta Nipponical journal style (http://monumenta.cc.sophia.ac.jp/MN_Style_Sheet.pdf) but have encountered difficulties disambiguating footnote references. When there are two works for the same author in the same year I would like the footnote reference to read, for example. "Sugimoto 1990a" or "Sugimoto 1990b". There seems to be an option for this with in-text citations but the only disambiguation I can find for footnotes is a check box for including the title in ambiguous cases. This option does not match the Monumenta Nipponica citation style (and in any case I can't seem to get it to work). Does any one have any suggestions for resolving this problem? Many thanks in advance.