Pro3.1 - Unique values, multiple fields, control which field is used to sort by?

[KeithAddison1]

Is there a way to control which field the legend sorts by when using unique values, multiple fields?

I have a legend for a 'heat' map that I want to read COMPANY_NAME, AGMT_EXPIRATION_DATE.  But I need it sorted by AGMT_EXPIRATION_DATE in order for the color ramp to makes sense.  But if I switch the order of the two fields then it sorts by COMPANY_NAME instead, which results in a meaningless color ramp.