Turn off the Free Shipping in the Modules ... Order Totals ... Shipping ot_shipping ...

Turn on the Modules ... Shipping ... Free Shipping Options freeoptions shipping module and set to Total >= 100.00 ...

Now the Free Shipping over $100 will show with your other shipping methods ...

NOTE: If that Flat Rate flat shipping module for the Express is only to show for orders over $100.00 ... then you will need to customize the module further ...