Reviewed and attempted to follow the above article with adjustment of months rather than days and getting an invalid return date.
Tried 90 days and 3 months and both returned same results Originally I thought bad value may be due to addDays possibly limiting to a single month
var DateUtils = org.apache.commons.lang.time.DateUtils;
var fromdate90 = qie.formatDate('YYYY-MM-DD', DateUtils.addMonths(qie.deduceDate(qie.getSystemDate()),-3));
qie.debug('fromdateCalced ' + fromdate90);
[path=1-2-3] - fromdateCalced 2020-03-63