The following script can be used for the "exit" action so the basic action to get the start date's number and then it can be used to compute the next days field values by adding the appropriate number of days. A more experienced user could use a control loop t0 modify the field names and number of days to add to the start date's day number for the additional date fields.
// Script for exit from date select field
// perform calculation only if an input date has been selected
if (HasValue(cInputDate)) then
// format string for the date fields
var cDateFormat = "MMM D, YYYY"
// intermediate information start - optional
xfa.host.messageBox(Concat("The input date formatted value is: ", cInputDate.formattedValue, "
The input date's numeric value: ", Date2Num($.formattedValue, cDateFormat), "
The adjusted date number is: ", (Date2Num($.formattedValue, cDateFormat) + 1), "
The adjusted date is: ", Num2Date(Date2Num($.formattedValue, cDateFormat) + 1) ),
"Intermediate Detail", 3, 0)
// intermediate information end - optional
var StartDateNumber = Date2Num($.formattedValue, cDateFormat)
// add 1 day to StartDateNumber
cAdjustDate = Num2Date(StartDateNumber + 1, cDateFormat)
// add code for additional date fields here adding appropriate number of days for date
else
cAdjustDate = "" // no input keep field blank
// add code for additional date fields here
endif