@rinosaur,
How about this ?
// Opem Sample Data
dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
// Write to Excel
Create Excel Workbook("C:\Test.xlsx",{"Big Class"},{"Big"});
// Open Another Sample Data Set
dt1 = Open( "$SAMPLE_DATA/Air Traffic.jmp" );
// Write both tables to existing workbook
Create Excel Workbook("C:\Test.xlsx",{"Big Class","Air Traffic"},{"Big","Air"});
However, in your case , you will directly append the data into a new tab in Excel to your workbook using the last step .
So - open you excel workbook as a JMP data table , then have a second data table with the data you want to write and then use Create Excel Workbook as shown above to write to Excel.
If you want all the data in the same tab , just join the JMP data tables and write to Excel . Hope this helps .
Best
Uday